CN111992694A - Configurable SiCp/Al-based composite material and preparation method thereof - Google Patents

Abstract

The invention provides a configurable SiCp/Al aluminum-based composite material and a preparation method thereof, wherein the method comprises the following steps: s1, mixing oxidized SiC particles with NiO₂Mixing the powder, and uniformly stirring and mixing the powder with a binder, a defoaming agent and a surfactant to form the composite materialCoating; s2, uniformly mixing the coating and the foam particles, filtering the mixture by using a screen, placing the mixture into a mold cavity, and pressing the mixture into a precast block; s3, drying and curing the precast block, and sintering at 700-900 ℃ for 2-3 h to form the precast block; s4, pouring aluminum alloy liquid into the die cavity of the die, and then placing the preheated precast block on the aluminum alloy liquid; or placing the preheated precast block in a mold cavity, and then pouring aluminum alloy liquid; then preparing the configurable SiCp/Al aluminum-based composite material by a pressure infiltration method. By NiO₂And SiO₂The oxide layer greatly improves the wettability of SiC and aluminum alloy; the polystyrene pre-expanded particles and the hydrolyzed tetraethoxysilane can construct SiC particle skeletons with controllable porosity.

Description

Configurable SiCp/Al-based composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of metal matrix composite preparation, and particularly relates to a configurable SiCp/Al aluminum matrix composite and a preparation method thereof.

Background

With the rapid development of modern science and technology, people have higher and higher requirements on materials, and besides excellent mechanical properties and good comprehensive properties of the materials, the materials are also required to have certain special properties. It is difficult for single engineering materials such as metal, ceramic, polymer, etc. to meet these performance requirements.

The composite material has a series of advantages of high specific strength, high specific modulus, low expansion, low density and the like. Particularly, Metal Matrix Composites (MMCs) have excellent mechanical properties, a series of metal characteristics such as electric conduction, heat conduction, wear resistance, size stability and the like, and are excellent structural materials.

In recent years, as the high integration of circuits and the rapid development of LED lighting and display technologies, the strength, heat dissipation and thermal stability of the substrate are gradually unsatisfactory, while the SiCp/Al aluminum-based composite material has the characteristics of good thermal conductivity, low expansion and high strength, and can meet the requirements. However, the preparation difficulty of the material is high, and the content of SiCp in the prepared material is uncontrollable and the combination degree of the SiCp and the aluminum alloy matrix is uncontrollable due to the uncontrollable addition of the SiCp and the poor wettability of the SiCp and the aluminum alloy matrix, so that the metal characteristics of the SiCp/Al aluminum-based composite material are influenced to a great extent, and the popularization and application of the material are limited.

Therefore, a new preparation method of the SiCp/Al aluminum-based composite material needs to be researched, so that the content, size and distribution of SiCp are controllable; the combination degree of SiCp and the aluminum alloy matrix is controllable; the shape and size distribution of the aluminum alloy matrix is controllable.

Disclosure of Invention

To solve the above problems, it is an object of the present invention to provide a configurable SiCp/Al-based composite material and a method for preparing the same, by NiO₂And oxidized SiC particles, the wettability of the SiC particles and the aluminum alloy is greatly improved; the polystyrene pre-expanded particles and the hydrolyzed tetraethoxysilane can construct a SiC particle framework with controllable porosity, and the problems that the addition amount of SiC particles is uncontrollable, the wettability with an aluminum alloy matrix is poor, the content of the SiC particles is uncontrollable and the bonding degree with the aluminum alloy is uncontrollable in the existing preparation method are solved.

In order to achieve the above object, the technical solution of the present invention is as follows.

A preparation method of a configurable SiCp/Al aluminum-based composite material comprises the following steps:

s1, mixing oxidized SiC particles with NiO₂Mixing the powder to form coating aggregate; then stirring and mixing the coating aggregate, the binder, the defoaming agent and the surfactant uniformly to form a coating; wherein NiO₂The mass of the powder is 2-5% of the mass of the oxidized SiC particles;

s2, mixing the coating of S1 with the foam particles uniformly to ensure that a layer of oxidized SiC particles and NiO are attached to the surfaces of the foam particles₂Filtering the powder by using a screen, placing the powder in a mold cavity, and pressing the powder into a precast block; wherein the volume ratio of the coating to the foam particles is 1: 3-5;

s3, drying and curing the prefabricated block of S2, and sintering at 700-900 ℃ for 2-3 h to form a hollow SiC particle spherical skeleton prefabricated block;

s4, pouring aluminum alloy liquid into the die cavity of the die, and then placing the preheated precast block on the aluminum alloy liquid; or placing the preheated precast block in a mold cavity, and then pouring aluminum alloy liquid; then preparing the configurable SiCp/Al aluminum-based composite material by a pressure infiltration method.

Further, in S1, the oxidized SiC particles were prepared as follows:

and carrying out oxidation reaction on the SiC particles for 2-3 h at the temperature of 1000-1300 ℃ to form an oxide layer on the surfaces of the SiC particles.

Furthermore, the particle size of the SiC particles is 5-30 μm.

Further, in S1, the binder is tetraethoxysilane and/or white latex, wherein the mass of the white latex is 0-3 wt% of the tetraethoxysilane; the mass ratio of the ethyl orthosilicate to the SiC particles is 1: 1-4.

Further, in S1, the mass of the defoaming agent is 0.1-0.2 wt% of the mass of the binder; the mass of the surfactant is 0.2-0.3 wt% of the mass of the binder.

Further, in S2, the preparation process of the foam particles is as follows:

introducing steam into the polystyrene resin beads and heating to pre-foam the polystyrene resin beads; wherein the diameter of the foamed foam particles is 0.1-2 mm.

Furthermore, the pressure for pressing into the precast block is less than or equal to 10 MPa.

Further, in S3, the temperature for drying and curing is 40-60 ℃ and the time is 5-8 h.

Further, in S4, the preparation process of the SiCp/Al aluminum matrix composite material can be configured as follows:

s4.1, placing the prefabricated block of the S3 in a resistance furnace, heating to 500-700 ℃, and preheating;

s4.2, preheating the die to 250-350 ℃; then pouring aluminum alloy liquid into a die cavity at the temperature of 720-750 ℃, and then placing the preheated precast block S4.1 on the aluminum alloy liquid;

or placing the prefabricated block preheated by S4.1 in a preheated die cavity, and then pouring aluminum alloy liquid at 720-750 ℃;

and S4.3, locking the die cavity of the S4.2, and maintaining the pressure at 10-40 MPa until the aluminum alloy is solidified to prepare the configurable SiCp/Al aluminum-based composite material.

The configurable SiCp/Al aluminum-based composite material prepared by the method.

The invention has the beneficial effects that:

1. the invention forms a layer of SiO on the surface of SiC particles by oxidizing the SiC particles at high temperature₂An oxide layer; the hydrolysis of ethyl orthosilicate can generate SiO₂Fibre gels and alcohols, SiO₂The fiber gel can greatly improve the coating strength, Si (OCH)₂CH₃)₄+2H₂O＝SiO₂+4C₂H₅OH；

And in the pressure infiltration process, SiO on the surfaces of Al and SiC particles₂Oxide layer and SiO generated after hydrolysis of tetraethoxysilane₂The fiber gel reacts to ensure the wettability of the matrix aluminum alloy and the SiC particles, thereby greatly improving the bonding degree of the aluminum alloy matrix and the SiC particles. 2Al +3SiO₂→2AlO₃+3Si。

NiO₂And the wettability of the aluminum alloy matrix and SiC particles can be further improved, so that the combination degree of the matrix aluminum alloy and the SiC particles is greatly improved.

2. In the high-temperature sintering process of the prefabricated block, additives such as foam and a bonding agent can be removed, and carbon and NiO formed after the additives such as the foam and the bonding agent are removed₂Reaction to CO₂And Ni, represented by the formula: c + NiO₂→CO₂+ Ni. This facilitates removal of carbon formed after sintering, and thus forms a hollow SiC particle spherical skeleton preform.

3. The method can prepare the SiCp/Al aluminum-based composite material with a controllable structure, wherein the size distribution and the content of SiC particles are controllable, the shape size distribution of an aluminum alloy matrix is controllable, and the controllability is mainly controlled by the particle size of the SiC particles and the particle size of polystyrene pre-foamed foam particles. Compared with the traditional vacuum pressure infiltration process, the method of the invention is simple and can be used for large-scale production.

4. The SiCp/Al aluminum-based composite material capable of constructing aluminum alloy matrix distribution and form distribution is prepared by a pressure infiltration method, and has the advantages of low expansion coefficient and high thermal conductivity.

Drawings

FIG. 1 is a flow chart of a process for preparing a configurable SiCp/Al-based composite material according to embodiments 1-3 of the present invention.

FIG. 2 is a schematic structural view of a pressure impregnation mold used in examples 1 to 3 of the present invention.

FIG. 3 is a schematic structural diagram of a configurable SiCp/Al-based composite material prepared in embodiments 1-3 of the present invention.

In the figure, 1, a jacking component; 2. a silicon carbide preform; 3. aluminum alloy liquid; 4. a pressing member; 5. an aluminum alloy substrate; 6. silicon carbide particles and an aluminum alloy matrix (with the aluminum alloy matrix in the interstitial spaces of the particles).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

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

Referring to fig. 1, a method for preparing a configurable SiCp/Al-based composite material includes the following steps:

s1 preparation of foam particles

Introducing steam into a stirring kettle for preheating, adding polystyrene resin (EPS) beads into the preheated stirring kettle, and introducing steam for heating to perform pre-foaming; wherein the diameter of the foamed foam particles is 0.1-2 mm;

s2, oxidized SiC particles

Placing the SiC particles in an industrial microwave sintering furnace, and carrying out high-temperature oxidation reaction for 3h at 1200 ℃ to form a layer of SiO on the surface of the SiC particles₂The oxide layer can increase the wettability of SiC particles and aluminum alloy; wherein, SiC particlesThe particle size of (A) is 5-30 μm;

s3 preparation of coating aggregate

Mixing oxidized SiC particles with NiO₂Mixing the powder to form coating aggregate; wherein NiO₂The mass of the powder was 3% of the mass of the oxidized SiC particles;

s4 preparation of coating

Mechanically stirring and uniformly mixing the coating aggregate, the binder, the defoaming agent and the surfactant by using a stirrer to form a coating;

wherein the binder is tetraethoxysilane, and the mass ratio of tetraethoxysilane to SiC particles is 1: 2;

the mass of the defoamer (purchased from Senson chemical Co., Ltd.) was 0.2 wt% of the mass of the binder; the mass of surfactant (purchased from Senson Seisaku chemical Co., Ltd.) was 0.3 wt% of the mass of the binder.

The function of the binder is to increase the adhesion between the coating and the polystyrene pre-expanded foam particles; the defoaming agent is used for eliminating bubbles in the coating; the surfactant serves to increase the coating and coating properties of the polystyrene pre-expanded particles.

The hydrolysis of ethyl orthosilicate can generate SiO₂Fibre gels and alcohols, SiO₂The fiber gel can greatly improve the strength of the coating, and meanwhile, the fiber gel is attached to the coating aggregate to improve the wettability of the aluminum alloy matrix and the SiC particles. Si (OCH)₂CH₃)₄+2H₂O＝SiO₂+4C₂H₅OH。

S5 preparation of precast block

Uniformly mixing the coating of S4 with the foam particles of S1 by a mixer to ensure that a layer of oxidized SiC particles and NiO are attached to the surfaces of the foam particles₂Pulverizing; fishing out by using a screen, filtering, placing in a die cavity when no coating flows out, pressing into a precast block by using a press, wherein the pressure is less than or equal to 10 MPa;

wherein the volume ratio of the coating to the foam particles is 1: 4; the thickness of the coating is 0.1-0.3 mm.

S6 preparation of hollow SiC particle spherical skeleton precast block

Drying and curing the prefabricated block of S5 in a drying oven at 50 ℃ for 6 h; then transferring the mixture into a high-temperature furnace, sintering the mixture for 3 hours at 800 ℃ for removing additives such as foam and adhesive, and removing the additives such as foam and adhesive to form carbon and NiO₂Reaction to CO₂And Ni, represented by the formula: c + NiO2 → CO2+ Ni; finally forming the hollow SiC particle spherical skeleton precast block.

S7 preparation of SiCp/Al-based composite material by pressure infiltration method

S7.1, placing the precast block of the S6 in a resistance furnace, heating to 600 ℃, and preheating;

s7.2, preheating the die to 300 ℃, then pouring aluminum alloy liquid into a die cavity at 740 ℃, and then placing the prefabricated block preheated in the S7.1 on the aluminum alloy liquid;

and S7.3, installing a locking device, as shown in figure 2, locking the die cavity of the S7.2, finally loading the pressure of 30MPa by using a press machine, and maintaining the pressure until the aluminum alloy is solidified, thus preparing the SiCp/Al-based composite material with the structural aluminum alloy matrix distribution and shape distribution, as shown in figure 3.

After pouring aluminum alloy liquid, SiO on the surface of Al and SiC particles₂SiO generated after hydrolysis of oxide layer and ethyl orthosilicate₂The reaction was carried out as shown in the following formula: 2Al +3SiO₂→2AlO₃+3Si；

The wettability of the matrix aluminum alloy and the SiC particles is ensured, and the combination degree of the matrix aluminum alloy and the SiC particles is greatly improved.

Example 2

A method of making a configurable SiCp/Al matrix composite, the method being the same as in example 1, except that:

in S2, the temperature of the high-temperature oxidation reaction is 1300 ℃, and the reaction time is 2 h;

in S3, NiO₂The mass of the powder is 5% of the mass of the oxidized SiC particles;

in S4, the binder is tetraethoxysilane and white latex, and the mass of the white latex is 3 wt% of the mass of the tetraethoxysilane after hydrolysis. The mass ratio of the ethyl orthosilicate to the SiC particles is 1: 4. The mass of the defoaming agent is 0.2 wt% of the mass of the binder; the mass of the surfactant was 0.3 wt% of the mass of the binder.

In S5, the volume ratio of the coating to the foam particles is 1: 5;

in S6, in a drying oven, drying and curing are carried out at the temperature of 60 ℃ for 5 hours;

in a high-temperature furnace, the sintering temperature is 900 ℃, and the sintering time is 2 hours;

s7.1, preheating the precast block at 700 ℃;

s7.2, preheating a mould to 350 ℃, then placing the prefabricated block preheated in S7.1 into a preheated mould cavity, and then pouring aluminum alloy liquid at 750 ℃;

in S7.3, the pressure applied by the press is 40 MPa.

Example 3

A method of making a configurable SiCp/Al matrix composite, the method being the same as in example 1, except that:

in S2, the temperature of the high-temperature oxidation reaction is 1000 ℃, and the reaction time is 3 h;

in S3, NiO₂The mass of the powder is 2% of the mass of the oxidized SiC particles;

in S4, the binder is hydrolyzed tetraethoxysilane and white latex, and the mass of the white latex is 2 wt% of the hydrolyzed tetraethoxysilane. The mass ratio of the ethyl orthosilicate to the SiC particles is 1: 1. The mass of the defoaming agent is 0.1 wt% of the mass of the binder; the mass of the surfactant was 0.2 wt% of the mass of the binder.

In S5, the volume ratio of the coating to the foam particles is 1: 3;

in S6, in a drying oven, drying and curing are carried out at the temperature of 40 ℃ for 8 h;

in a high-temperature furnace, the sintering temperature is 700 ℃, and the sintering time is 3 h;

s7.1, preheating the precast block at 500 ℃;

s7.2, preheating the die to 250 ℃, and then pouring aluminum alloy liquid into a die cavity when the temperature is 720 ℃;

in S7.3, the pressure loaded by the press is 10 MPa.

Fig. 2 is a schematic structural diagram of a pressure infiltration mold used in embodiments 1 to 3 of the present invention. The die cavity is arranged in the locking part, after the aluminum alloy liquid 3 and the silicon carbide prefabricated part 4 are added into the die cavity, the pressing part 1 is pressed downwards and the pressing part 4 is pressed upwards, so that the aluminum alloy liquid is infiltrated towards the silicon carbide prefabricated part due to the pressure, the pressure is maintained until the aluminum alloy is solidified, and the SiCp/Al aluminum-based composite material capable of constructing the distribution and the form distribution of the aluminum alloy matrix can be prepared, as shown in figure 3, the aluminum alloy matrix is arranged in the hollow pores of the SiC particle spherical framework prefabricated block, and the aluminum alloy matrix is arranged in the gaps of the silicon carbide particles.

The performance of the SiCp/Al aluminum-based composite material prepared in the embodiments 1-3 of the invention is basically the same, so that the performance characterization is only carried out on the SiCp/Al aluminum-based composite material in the embodiment 1, and the results are shown in the following table 1.

TABLE 1 SiCp/Al-based composites with different SiC particle contents

According to the results in table 1, it can be seen that the SiCp/Al aluminum matrix composite material with structural aluminum alloy matrix distribution and morphology distribution prepared by the pressure infiltration method in example 1 of the present invention has a low expansion coefficient and a high thermal conductivity.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A preparation method of a configurable SiCp/Al aluminum-based composite material is characterized by comprising the following steps:

s1, mixing oxidized SiC particles with NiO₂Mixing the powder to form coating aggregate; then stirring and mixing the coating aggregate, the binder, the defoaming agent and the surfactantMixing uniformly to form a coating;

wherein NiO₂The mass of the powder is 2-5% of the mass of the oxidized SiC particles;

s2, mixing the coating of S1 with the foam particles uniformly to ensure that a layer of oxidized SiC particles and NiO are attached to the surfaces of the foam particles₂Filtering the powder by using a screen, placing the powder in a mold cavity, and pressing the powder into a precast block; wherein the volume ratio of the coating to the foam particles is 1: 3-5;

s3, drying and curing the prefabricated block of S2, and sintering at 700-900 ℃ for 2-3 h to form a hollow SiC particle spherical skeleton prefabricated block;

s4, pouring aluminum alloy liquid into the die cavity of the die, and then placing the preheated precast block on the aluminum alloy liquid; or placing the preheated precast block in a mold cavity, and then pouring aluminum alloy liquid; then preparing the configurable SiCp/Al aluminum-based composite material by a pressure infiltration method.

2. The method of making a configurable SiCp/Al based composite material according to claim 1 wherein in S1 the oxidized SiC particles are prepared as follows:

and carrying out oxidation reaction on the SiC particles for 2-3 h at the temperature of 1000-1300 ℃ to form an oxide layer on the surfaces of the SiC particles.

3. The method of claim 2, wherein the SiC particles have a size of 5 to 30 μm.

4. The method for preparing the configurable SiCp/Al-based composite material as claimed in claim 1, wherein in S1, the binder is tetraethoxysilane and white latex, wherein the white latex has a mass of 0-3 wt% of the tetraethoxysilane; the mass ratio of the ethyl orthosilicate to the SiC particles is 1: 1-4.

5. The method of claim 1, wherein in S1, the mass of the defoaming agent is 0.1 to 0.2 wt% of the mass of the binder; the mass of the surfactant is 0.2-0.3 wt% of the mass of the binder.

6. The method of making a configurable SiCp/Al based composite material according to claim 1, wherein in S2 the foam particles are prepared as follows:

introducing steam into the polystyrene resin beads and heating to pre-foam the polystyrene resin beads;

wherein the diameter of the foamed foam particles is 0.1-2 mm.

7. The method of claim 1 wherein the pressure at which the preform is pressed is less than or equal to 10 MPa.

8. The method of claim 1, wherein the drying and curing temperature of S3 is 40-60 ℃ for 5-8 h.

9. The method of claim 1, wherein in S4, the configurable SiCp/Al-based composite is prepared by:

s4.1, placing the prefabricated block of the S3 in a resistance furnace, heating to 500-700 ℃, and preheating;

s4.2, preheating the die to 250-350 ℃; then pouring aluminum alloy liquid into a die cavity at the temperature of 720-750 ℃, and then placing the preheated precast block S4.1 on the aluminum alloy liquid;

or placing the prefabricated block preheated by S4.1 in a preheated die cavity, and then pouring aluminum alloy liquid at 720-750 ℃;

and S4.3, locking the die cavity of the S4.2, and maintaining the pressure at 10-40 MPa until the aluminum alloy is solidified to prepare the configurable SiCp/Al aluminum-based composite material.

10. A configurable SiCp/Al based composite material prepared by the method of any one of claims 1 to 9.

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