CN114292126A - A kind of preparation method of porous ceramic local reinforcement composite material automobile brake pad - Google Patents

Abstract

The invention discloses a preparation method of a porous ceramic local reinforced composite material automobile brake pad, belongs to the field of material processing engineering, and aims to solve the technical problem of continuous local reinforced integrated forming by taking an automobile brake pad as a typical part, thereby realizing the light weight and high performance of the automobile brake pad, shortening the production period, improving the material utilization rate and prolonging the service life of the brake pad. According to the invention, an organic foam impregnation method is adopted for sintering to prepare a large-size continuous porous ceramic preform, and a liquid die forging integrated forming technology is adopted, and quantitative pouring is adopted to prepare typical workpieces such as a continuous porous ceramic local reinforced composite material automobile brake pad and the like with high size precision and good wear resistance. The invention is applied to parts with high wear resistance requirements, such as automobile brake pads, automobile hubs, automobile pistons and the like, of local reinforced composite material structures.

Description

A kind of preparation method of porous ceramic local reinforced composite material automobile brake pad

technical field

The invention belongs to material processing engineering, and particularly relates to a preparation method of a porous ceramic partially reinforced composite material automobile brake pad.

Background technique

Brake pads are the key parts in the automobile braking system. High-quality automotive brake pads need to have high tensile strength, wear resistance, heat resistance and vibration damping. Judging from the development history of brake pads, the currently widely used brake pad materials mainly include ordinary cast iron, low alloy cast iron, ordinary cast steel, special alloy cast steel, low alloy forged steel and cast iron-cast steel (forged steel) composite materials. The material of cast iron brake pads is mainly gray cast iron, including four typical grades such as HT150, HT200, HT250 and HT300. Most of the existing automobile brake pads are made of cast iron, and they are developing in the direction of forged steel materials. The strength of special forged steel brake pads is about twice as high as that of cast iron brake pads. However, both cast iron and forged steel have shortcomings such as long manufacturing cycle, poor thermal conductivity and easy occurrence of thermal cracks, which greatly affect the performance of automobiles. Deformation, thermal cracking and abnormal wear of the brake pads are the main failure problems. To avoid or reduce the occurrence of the above failures, the selection of brake pad materials is very critical. The main solution at present is to optimize the material by adding trace elements to improve the performance of brake pads.

With the increasingly strong requirements for automobile lightweight, aluminum-based composite brake pads have begun to be used in automotive brake pads. For example, Ford has developed SiCp/Al aluminum-based composite brake pads, replacing conventional cast iron brake pads and mass-produced them. For Lincoln Town Car; Lotus company applies aluminum matrix composites to front and rear brake pads of sports sedan (Elise). Qi Haibo et al. used liquid die forging to prepare 20% SiC _p /Al composite material, and its tensile strength reached 320 MPa, which is about 28% higher than that of cast iron HT250, which can fully meet the requirements of the strength index of brake pads. Through the working conditions of repeated continuous braking, it is found that the surface temperature rise of the SiC _p /Al composite brake pad is low and the friction coefficient is stable. In the brake wear test, the mass wear of SiCp A composite brake pads is about 1/4 of that of cast iron brake pads. Zou Maohua et al. used the centrifugal casting process to prepare endogenous particle reinforced Mg ₂ Si/Al composites. By adding SiC, primary Si and primary Mg ₂ Si can be obtained during centrifugal casting. By adding Cu, Ni and other alloying elements, After strengthening the matrix and performing T6 treatment, a material with a hardness (HRB) of 89.6 and good wear resistance can be obtained, and both hardness and wear resistance can meet the performance requirements for making brake pads. The replacement of cast iron brake discs with aluminum-based composite brake discs with light weight and excellent performance will become the development direction of brake pad preparation in the future.

In order to seek a high wear-resistant aluminum alloy and aluminum-based composite materials to prepare high-performance automobile brake pads, researchers at home and abroad have carried out research and development, preparation and performance optimization of related materials. Currently developed high wear-resistant aluminum alloy materials mainly include particle reinforced aluminum matrix composite materials, fiber reinforced aluminum matrix composite materials and so on. Generally, ceramic particles and short fibers such as SiC, Al ₂ O ₃ and ZrO ₂ are added to locally enhance the properties to prepare particle-reinforced aluminum matrix composites. However, the added ceramic particles and ceramic fibers have poor wettability and are prone to agglomeration, which makes the preparation difficult and the performance of the material parts is difficult to control. If a special preparation process is adopted, higher requirements are placed on the equipment, which greatly increases the cost of production. Therefore, it is of significant practical significance and application value to explore and develop a preparation and forming process of aluminum matrix composites with simple process operation, excellent and stable performance, and provides a new preparation idea and research and development direction for the preparation of lightweight and high wear-resistant automobile brake pads. .

SUMMARY OF THE INVENTION

The invention aims to solve the technical problem of local reinforcement integrated forming with automobile brake pads as typical parts, thereby realizing the lightweight and high performance of automobile brake pads, shortening the production cycle, improving the utilization rate of materials, and prolonging the service life of the brake pads. The invention adopts the organic foam impregnation method to sinter to prepare the large-size continuous porous ceramic preform, and adopts the liquid die forging integrated forming technology and quantitative pouring to prepare the continuous porous ceramic local reinforced composite material automobile with high dimensional accuracy and good wear resistance. The utility model relates to a brake pad, specifically a liquid die forging integrated forming technology of a large-size continuous porous ceramic partially reinforced composite material automobile brake pad.

To this end, the present invention provides an efficient and simple liquid die forging integrated forming method for large-size continuous porous ceramic locally reinforced aluminum alloy structural parts, which is used to prepare and produce lightweight, high wear-resistant, high-strength continuous local reinforced composite materials for automobiles It is a typical part of brake pads, and based on this, it will expand its application in the engineering forming design and production of locally reinforced composite structural parts such as aluminum alloy composite materials and magnesium alloy composite materials.

A preparation method of a porous ceramic partially reinforced composite material automobile brake pad of the present invention comprises the following steps:

Step 1. Preparation of Porous Ceramic Preforms

The porous ceramic preform is prepared by the organic foam impregnation method. The specific process is as follows:

1) The pretreatment of organic foam includes three processes: alkaline solution treatment, surfactant treatment and binder treatment: first, after the organic foam is cut into a specified shape, it is placed in a 10wt.% to 20wt.% NaOH solution, Soak for 2 hours under the constant temperature condition of 40-60 ℃ water bath, after soaking, rub repeatedly and rinse with clean water, then dry for use; then use 1wt.%～2wt.% CMC solution to soak the organic foam for 1 hour; finally, use 15wt.% ～20wt.% of silica sol was soaked in organic foam for 1h, to be used for hanging pulp;

2) Add materials in the order of ceramic aggregate, sintering aid, high temperature binder, low temperature binder, dispersant, rheological agent, surfactant and slurry solvent, and the forward rotation speed of the stirring motor is 400~600r After stirring for 20 to 40 minutes at a speed of The proportion of material is 45wt.%～55wt.%, the mass of sintering aid is 9wt.%～12wt.%, the mass of high temperature binder is 4wt.%～5wt.%, and the mass of low temperature binder is 15wt.%. %～18wt.%, the mass proportion of dispersant is 0.2wt.%～0.5wt.%, the mass proportion of rheology agent and surfactant is 0.2wt.%～0.5wt.%, and the mass proportion of defoamer is 0.2wt% .%～0.5wt.%, the rest is distilled water;

3) extruding the organic foam processed in step 1) to discharge the air, placing it in a slurry-hanging mold, and immersing the entirety of the mold in the ceramic slurry obtained in step 2), so that it is fully absorbed until the air inside is completely eliminated; Take out the controllable dry, place it on the working platform, and blow it dry; immerse it in the ceramic slurry again; repeat the slurry 4-6 times; prepare the porous ceramic green body, that is, complete the organic foam hanging slurry;

4) Sintering the organic foam after sizing in step 3), and the specific sintering process is as follows: the temperature rises from room temperature to 200°C at a heating rate of 6-7°C/min; and then increases from 200°C at a heating rate of 1°C/min The temperature was raised to 700°C, and after holding at 700°C for 120 minutes, the temperature was increased from 700°C to 1500°C at a heating rate of 5°C/min; The temperature is lowered from 1500°C to 1000°C, and finally cooled with the furnace to obtain a porous ceramic preform;

Step 2. Partially enhanced integrated molding of automobile brake pads with porous ceramics

Through liquid die forging, the alloy matrix and the porous ceramic ceramic preform are integrally formed to prepare the porous ceramic partial reinforced composite material automobile brake pad.

Further, the ceramic material is Al ₂ O ₃ , ZrO ₂ , SiC or TiB ₂ .

Further, the organic foam is polyurethane foam or polyester foam.

Further, the aluminum alloy matrix is Al-Mg-Si series, Al-Mg-Si-Cu series, Al-Zn-Mg-Cu series aluminum alloy or Mg-Al-Zn series magnesium alloy.

Further, the sintering aid is silica powder or kaolin; the high temperature binder is bentonite or talc powder; the low temperature binder is industrial silica sol; the dispersant is polyacrylamide aqueous solution ; The rheological agent and the surfactant are both carboxymethyl cellulose aqueous solutions; the defoaming agent is n-octanol; the slurry solvent is distilled water.

Further, the viscosity of the ceramic slurry is 300-400 mPa.S, and the opening angle is 12%-15%.

Further, the sintering described in step 4) is carried out using a KJ-SJ17 high temperature lifting furnace.

Further, in step 2), the proportion of ceramic aggregate in the ceramic slurry is 45wt.% to 55wt.%, the mass of sintering aid is 12wt.%, the mass of high-temperature binder is 5wt.%, and the mass of low-temperature binder is 5wt.%. The mass ratio is 15wt.%, the mass ratio of dispersant is 0.2wt.%, the mass ratio of rheology agent and surfactant is 0.2wt.%, and the mass ratio of defoamer is 0.5wt.%.

Further, in step 3), the organic foam is taken out after being saturated and controlled to be dried until there is no continuous slurry flow.

Further, in step 3), the two sides of the organic foam body are blown dry in turn after being saturated to ensure the uniformity of slurry coating.

The principle of the invention lies in: preparing a porous ceramic preform with a partial shape of a workpiece by an organic foam impregnation method, and using a liquid die forging integrated forming process to prepare a composite material automobile brake pad with locally enhanced performance. In the preparation process of the porous ceramic preform, the selection of ceramic particles (Al ₂ O ₃ , ZrO ₂ , SiC or TiB ₂ and other powders) and the control of the composition ratio (the optimal solid phase ratio of the slurry is determined to be 65wt.%～ 75wt.%), optimization of the sintering process plan, etc. to improve the strength, hardness, porosity, thermal shock resistance and structural integrity of the preform, so as to improve its local reinforcement effect inside the aluminum matrix composite. In the process of preparing and forming porous ceramic partially reinforced composite automobile brake pads, high temperature solidification, plastic deformation and local feeding of liquid metal are used to enhance the bonding strength of aluminum alloy matrix and porous ceramic preform, and improve the overall strength of automobile brake pads. Wear resistance and performance.

The present invention includes the following beneficial effects:

1) The porous ceramic preform of the present invention is an important component to ensure high wear resistance of automobile brake pads. The preparation process of the porous ceramic preform determines the structure and performance of the continuous porous ceramic to locally enhance the automobile brake pad. The present invention uses organic foam impregnation. method to prepare large-scale continuous porous ceramic preforms. The organic foam impregnation method has the advantages of simple process, convenient operation and low manufacturing cost, and is an economical, practical and promising porous ceramic preparation process for preparing porous ceramics with high porosity. Its unique feature is that with the help of the three-dimensional network structure of the organic foam, a large-scale continuous porous ceramic with network pores is obtained by uniformly coating the ceramic slurry on the organic foam and then sintering at high temperature after drying. In the present invention, a large-size continuous porous ceramic preform with certain strength and high porosity can be prepared by selecting suitable organic foam, ceramic powder, solvent and additives, and through pretreatment, sizing and sintering.

2) In the present invention, the sintering preparation of porous ceramic preforms is combined with the integrated forming process of liquid die forging, and the typical structural parts of aluminum matrix composite materials with continuous local reinforcement of porous ceramics can be prepared and obtained. On the one hand, the preparation of porous ceramic preforms ensures the continuous integrity of reinforced ceramics in the aluminum matrix, and improves the effect of local enhancement of the performance of aluminum matrix composites. On the other hand, the integration of liquid die forging realizes the reinforcement phase in the aluminum alloy matrix. The uniform and controllable distribution of aluminum alloy improves the bonding strength between the aluminum alloy matrix and the reinforcing phase, and optimizes the performance of aluminum matrix composite parts. At the same time, the integrated forming process in the present invention realizes near-net green production, reduces the preparation process, and saves material and time costs.

Description of drawings

Figure 1. Schematic diagram of the assembly of liquid die forging forming die for automobile brake pads; in the figure, 1-upper die plate, 2-upper die, 3-upper die jacket, 4-lower die jacket, 5-lower die, 6-bolt, 7-top Rod, 8-bolt, 9-brake piece, 10-pallet, 11-bolt, 12-lower die jacket, 13-positioning pin, 14-lower die pad;

Figure 2 is a flow chart of the preparation process of the porous ceramic preform;

Figure 3 is a physical diagram of a continuous porous ceramic preform;

Figure 4. Flow chart of the integrated forming process of porous ceramic partially reinforced composite automobile brake pads;

Figure 5. Physical image of continuous porous ceramic locally reinforced composite automobile brake pads.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the spirit of the contents disclosed in the present invention will be described in detail below. Changes and modifications may be made to the techniques taught without departing from the spirit and scope of this disclosure.

The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

Example

Taking Al ₂ O ₃ porous ceramics and the organic foam as polyurethane foam as an example, the brake pads were prepared according to the process shown in Figures 2 and 4.

Figure 2 is a flow chart of the preparation process of the porous ceramic preform, which shows the control of the porous ceramic preform structure and performance factors such as material selection, slurry preparation, and high temperature sintering during the preparation of the porous ceramic preform. Figure 4 is a schematic diagram of the integrated forming process of porous ceramic partially reinforced composite automobile brake pads. According to the size and use requirements of the automobile brake pads, a liquid die forging forming die (Figure 1) for preparing the automobile brake pads is designed and smelted according to the alloy. , mold preheating, liquid die forging and other processes can realize the forming and continuous production of porous ceramic partially reinforced composite automobile brake pads.

The preparation method of a porous ceramic partially reinforced composite material automobile brake pad of the present embodiment comprises the following steps:

Step 1. Preparation of Porous Ceramic Preforms

The porous ceramic preform is prepared by the organic foam impregnation method. The specific process is as follows:

1) Surface modification of the organic foam while ensuring the hardness of the organic foam, improving the wettability and adhesion between the organic foam and the slurry, and increasing the coating thickness of the organic foam surface slurry. The pretreatment of organic foam includes three processes: alkaline solution treatment, surfactant treatment and binder treatment: First, the organic foam is cut into a specified shape, placed in a 10wt.% NaOH solution, and heated in a water bath at 60°C Soak for 2 hours, rub repeatedly and rinse with water after soaking, measure its weight loss after drying, and dry it for use; then use 1 wt.% CMC solution to soak the organic foam for 1 hour; finally use 20 wt.% industrial silica sol to Soak in organic foam for 1 hour, ready to hang pulp for use;

₂ ) select Al ₂ O powder as ceramic aggregate, silica powder and kaolin as sintering aid, bentonite and talcum powder as high temperature binder, industrial silica sol as low temperature binder, polyacrylamide aqueous solution as dispersant, Carboxymethyl cellulose aqueous solution is rheology agent and surfactant, n-octanol is defoamer, and distilled water is slurry solvent. The ceramic slurry is prepared according to the solid phase ratio (the mass of ceramic aggregate is 45wt.%), in which the mass of sintering aid is 12wt.%, the mass of high-temperature binder is 5wt.%, and the mass of low-temperature binder is 15wt.% %, the mass of dispersant is 0.2wt.%, the mass of rheology agent and surfactant is 0.2wt.%, the mass of defoamer is 0.5wt.%, and the rest is distilled water. Add the ceramic slurry ingredients in the order of sintering aid, high temperature binder, a small amount of water, dispersant, rheological agent, low temperature binder and ceramic powder. After replenishing the water to the preset weight, stir with a stirring motor (speed 500r/ min), add the defoamer n-octanol after forward rotation for 30 minutes, and obtain ceramic slurry with certain viscosity and fluidity (viscosity 300～400mPa.S, opening angle 12%～15%) after reverse rotation for 10 minutes;

3) Squeeze the treated organic foam to expel the air, place it in the slurry-hanging mold, and immerse the mold as a whole in the prepared ceramic slurry, so that it is fully absorbed until the air inside is completely eliminated; take it out and control it to dry until no more Continuously flow the slurry and place it on the working platform. It is evenly blown dry by pneumatic equipment. After turning it over, it is blown dry again to ensure the uniformity of the slurry; it is immersed in the ceramic slurry again, and the slurry is repeatedly hung for 4-6 times to ensure the slurry. It is uniformly coated on the network structure of the organic foam, and a ceramic blank layer with a certain thickness (subject to complete covering of the foam) is formed; the porous ceramic blank is prepared to complete the organic foam hanging.

4) The porous ceramic preform was prepared by sintering the KJ-SJ17 high temperature lifting furnace according to the formulated sintering process plan. The specific sintering process is as follows: according to the heating rate of 6.6 ℃/min from room temperature to 200 ℃; then according to 1 ℃/min The heating rate of min was increased from 200 °C to 700 °C, and after holding at 700 °C for 120 minutes, the temperature was increased from 700 °C to 1500 °C at a heating rate of 5 °C/min; The cooling rate is lowered from 1500 °C to 1000 °C, and finally cooled with the furnace to obtain a porous ceramic preform;

Step 2. Partially enhanced integrated molding of automobile brake pads with porous ceramics

Through liquid die forging, the alloy matrix and the porous ceramic ceramic preform are integrally formed to prepare the porous ceramic partial reinforced composite material automobile brake pad.

According to the use requirements of automobile brake pads, a forming mold for preparing automobile brake pad blanks is designed, and the integrated forming and preparation of porous ceramic partially reinforced composite automobile brake pads is completed according to the processes of melting, preheating, and forming. The test equipment is mainly Including press, alloy smelting equipment, mold heating device and corresponding control device, the pressure device is X323-500B 5000KN four-column hydraulic press, and the smelting equipment is SDL-FZ-500 non-ferrous metal melting and holding furnace.

The sintered large-size continuous porous ceramic preform is prepared according to the flow chart of the preparation process of the porous ceramic preform shown in FIG. 2 , and the obtained porous ceramic preform is shown in FIG. 3 . In this example, high-temperature sintering of Al ₂ O ₃ porous ceramics is used to prepare Al ₂ O ₃ porous ceramic preforms with high porosity, high compressive strength and complete structure (porosity reaches 55%, compressive strength reaches 180.94 MPa, no macro cracks).

The continuous Al ₂ O ₃ porous ceramic partial aluminum matrix composite automobile brake pads (as shown in Figure 5 ) were prepared according to the integrated forming scheme of the porous ceramic partial reinforced composite automobile brake pads shown in Figure 4. The specific procedures are as follows: As shown in Figure 1, the liquid die forging forming die of the automobile brake pad is installed on the hydraulic press; the melting furnace is started, and after the melting furnace is preheated, the clean and dry aluminum alloy billet is placed in the furnace, and the temperature is heated and melted; the forming die resistance wire power supply Turn _on , set the mold temperature and heat it up. When the mold temperature reaches 100℃-200℃, the mold surface is sprayed with graphite, and then the mold is closed and heated _; Heat preservation; refining after the aluminum alloy is completely melted; start the hydraulic press when the aluminum alloy melt temperature (730°C) and the mold temperature (300°C) reach predetermined values; after the mold is opened, the Al ₂ O ₃ porous ceramic preform is put into the In the mold, the quantitative liquid aluminum alloy is poured into the mold, the mold is closed and pressurized, and the mold is opened for 40s to form a continuous Al ₂ O ₃ ceramic partially reinforced aluminum alloy composite material for automobile brake pads; after the workpiece is cooled for 5 minutes After ejection and removal, the next automobile brake pad can be formed and prepared, so as to realize the continuous production of parts.

Figure 1 is a schematic diagram of the assembly of the liquid forging forming die for automobile brake pads, showing the process principles of liquid infiltration, high temperature forming and local feeding in the liquid forging forming process of automobile brake pads;

As shown in Figure 1, the mold is assembled on the press beam and the worktable through the upper die plate 1 and the lower die plate 14. The upper die 2 and the upper die cover 3 are connected by bolts to form a forming die punch, while the lower die cover 4 and the lower die cover The die 5, the tray 10, and the lower die jacket 12 constitute the die concave die, and the cavity formed by the concave die and the punch die is used to realize the forming of the molten metal under the pressure of the die during liquid forging. The mold is designed with a local loading and feeding device, which can pressurize and feed the brake pad part 9 during the forming process, so as to improve the structure and performance of the part and the bonding strength between the porous ceramic and the matrix. After the forming mold is assembled, according to the processes of alloy matrix smelting, mold and preform preheating, liquid forging and forming, etc., the forming and preparation of porous ceramic partially reinforced automobile brake pads is completed. The test equipment mainly includes presses, alloy melting equipment, and mold heating devices. and corresponding controls.

Compared with the prior art, the improved method for preparing and forming porous ceramic partially reinforced composite material automobile brake pads effectively solves the problems of easy deformation, thermal cracking and abnormal wear of the currently commonly used gray cast iron brake pads, and improves the existing particle-reinforced aluminum matrix composite materials. Due to the agglomeration of the reinforcing phase and poor wettability of the material, by combining the sintering preparation of porous ceramic preforms with the integrated forming process of liquid die forging, a locally reinforced aluminum alloy with light weight, good bonding strength and excellent wear resistance was prepared. Matrix composite automotive brake pads.

The friction coefficient of the Al ₂ O ₃ -2A50 composite automobile brake pads prepared by the method of this example is 0.45 and the wear rate is 7.427mg/(km·N), while the friction coefficient of the commonly used gray cast iron is 0.56 and the wear rate is 21.827 mg/(km·N), so the composite automobile brake pads prepared in this example have excellent wear resistance. At the same time, the shear strength of the Al ₂ O ₃ -2A50 composite automobile brake pads reaches 119.63MPa, and the integrated bonding strength of the parts is relatively high. The weight of the Al ₂ O ₃ -2A50 composite automobile brake pads prepared in the examples is 3.8-4.3Kg, and the weight of the gray cast iron automobile brake pads is 11-12Kg).

The method of this embodiment realizes the continuous, stable and controllable distribution of the ceramic reinforcing phase in the aluminum alloy matrix, improves the bonding performance of the porous ceramic and the aluminum alloy matrix, and improves the performance and life of the automobile brake pad. Through the integrated forming of liquid die forging, the utilization rate of materials is improved, the process is reduced, the preparation and production practice is shortened, and the production efficiency is improved. In addition to aluminum-based composite parts, this method is also suitable for the preparation and production of locally reinforced typical structural parts such as magnesium alloy composite materials and nickel-based high-temperature composite materials. It is important for the performance optimization and lightweight production of typical structural parts. engineering significance and application value.

Claims (10)

1. A preparation method of a porous ceramic local reinforced composite material automobile brake pad is characterized by comprising the following steps:

step one, preparation of porous ceramic preform

The porous ceramic preform is prepared by an organic foam impregnation method, and the specific process comprises the following steps:

1) the pretreatment of the organic foam comprises three processes of alkali solution treatment, surfactant treatment and binder treatment: firstly, cutting organic foam into a specified shape, placing the organic foam into 10-20 wt.% NaOH solution, soaking for 2 hours in a water bath at the constant temperature of 40-60 ℃, repeatedly kneading after soaking, washing with clear water, and airing for later use; soaking the organic foam for 1h by adopting a CMC solution with the weight percentage of 1-2 wt.%; finally, soaking the organic foam for 1h by adopting 15-20 wt.% of silica sol to prepare a ready-to-be-pasted solution for later use;

2) sequentially feeding ceramic aggregate, a sintering aid, a high-temperature binder, a low-temperature binder, a dispersing agent, a rheological agent, a surfactant and a slurry solvent, stirring for 20-40 min at the forward rotation speed of a stirring motor of 400-600 r/min, adding a defoaming agent, and stirring for 5-15 min at the reverse rotation speed of the stirring motor of 400-600 r/min; obtaining ceramic slurry; wherein, the ceramic aggregate accounts for 45 wt.% to 55 wt.% in the ceramic slurry, the sintering aid accounts for 9 wt.% to 12 wt.%, the high-temperature binder accounts for 4 wt.% to 5 wt.%, the low-temperature binder accounts for 15 wt.% to 18 wt.%, the dispersant accounts for 0.2 wt.% to 0.5 wt.%, the rheological agent accounts for 0.2 wt.% to 0.5 wt.%, the defoaming agent accounts for 0.2 wt.% to 0.5 wt.%, and the balance is distilled water;

3) extruding the organic foam treated in the step 1) to discharge air, placing the organic foam in a slurry coating mold, and integrally soaking the organic foam together with the mold into the ceramic slurry obtained in the step 2) to fully absorb the air until the air in the organic foam is completely discharged; taking out, drying, placing on a working platform, and drying; immersing the ceramic slurry again; repeatedly coating the pulp for 4-6 times; preparing and obtaining a porous ceramic blank, namely finishing organic foam slurry coating;

4) sintering the organic foam subjected to slurry coating in the step 3), wherein the specific sintering process is as follows: heating the mixture from room temperature to 200 ℃ at a heating rate of 6-7 ℃/min; then heating from 200 ℃ to 700 ℃ at the heating rate of 1 ℃/min, preserving the heat at 700 ℃ for 120min, and then heating from 700 ℃ to 1500 ℃ at the heating rate of 5 ℃/min; keeping the temperature at 1500 ℃ for 120min, cooling from 1500 ℃ to 1000 ℃ at a cooling speed of 8-9 ℃/min, and finally cooling along with a furnace to obtain a porous ceramic preform;

step two, the porous ceramic local reinforced automobile brake pad is integrally formed

And (3) integrally forming the alloy matrix and the porous ceramic prefabricated body by liquid die forging forming to prepare the porous ceramic local reinforced composite material automobile brake pad.

2. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the ceramic material is Al₂O₃、ZrO₂SiC or TiB₂。

3. The method of claim 1, wherein the organic foam is polyurethane foam or polyester foam.

4. The method for preparing the porous ceramic local reinforced composite material automobile brake pad according to claim 1, wherein the aluminum alloy matrix is Al-Mg-Si series, Al-Mg-Si-Cu series, Al-Zn-Mg-Cu series aluminum alloy or Mg-Al-Zn series magnesium alloy.

5. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the sintering aid is silica powder or kaolin; the high-temperature binder is bentonite or talcum powder; the low-temperature binder is industrial silica sol; the dispersant is polyacrylamide aqueous solution; the rheological agent and the surfactant are carboxymethyl cellulose aqueous solution; the defoaming agent is n-octanol; the slurry solvent is distilled water.

6. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the viscosity of the ceramic slurry is 300-400 mPa.S, and the opening angle is 12-15%.

7. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the sintering in the step 4) is performed by using a KJ-SJ17 high temperature lift furnace.

8. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the ceramic aggregate ratio in the ceramic slurry in the step 2) is 45 wt.% to 55 wt.%, the sintering aid mass ratio is 12 wt.%, the high-temperature binder mass ratio is 5 wt.%, the low-temperature binder mass ratio is 15 wt.%, the dispersing agent mass ratio is 0.2 wt.%, the rheological agent and the surfactant mass ratio is 0.2 wt.%, and the defoaming agent mass ratio is 0.5 wt.%.

9. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the organic foam is taken out after full absorption in the step 3) and is drained until no continuous pulp flow exists.

10. The method for preparing the porous ceramic locally reinforced composite material automobile brake pad according to claim 1, wherein the organic foam is blown dry on two sides in turn after saturated absorption in the step 3), so that the uniformity of slurry coating is ensured.

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