阅读说明：本技术 碳化硅颗粒的预处理方法及铝基复合材料的制备方法 (Pretreatment method of silicon carbide particles and preparation method of aluminum matrix composite ) 是由 刘春轩 高平平 蒋兆汝 曹柳絮 张扬 戴青松 罗任 苏新 吴云 蒋小汉 于 2021-07-13 设计创作，主要内容包括：本申请涉及碳化硅颗粒的预处理方法及铝基复合材料的制备方法,通过在碳化硅颗粒表面形成二氧化硅层,再对其进行蚀刻,以制造表面孔洞,一方面二氧化硅层可与铝合金原料粉中的合金元素作用形成界面产物,提高碳化硅颗粒与铝合金原料粉之间的润湿性及界面结合强度,另一方面,表面孔洞使得铝合金原料粉与碳化硅颗粒之间还可以通过物理铆合作用进一步增强连接性能,减少因膨胀系数差异出现的界面脱离现象,因此,可实现铝基复合材料中碳化硅颗粒的质量含量达到50％～70％。(The application relates to a pretreatment method of silicon carbide particles and a preparation method of an aluminum matrix composite, a silicon dioxide layer is formed on the surface of the silicon carbide particles, and then the silicon dioxide layer is etched to manufacture surface holes, on one hand, the silicon dioxide layer can act with alloy elements in aluminum alloy raw material powder to form an interface product, so that the wettability and the interface bonding strength between the silicon carbide particles and the aluminum alloy raw material powder are improved, on the other hand, the surface holes enable the connection performance between the aluminum alloy raw material powder and the silicon carbide particles to be further enhanced through a physical riveting effect, and the interface separation phenomenon caused by the difference of expansion coefficients is reduced, so that the mass content of the silicon carbide particles in the aluminum matrix composite can reach 50% -70%.)

1. A pretreatment method of silicon carbide particles is characterized by comprising the following steps:

providing silicon carbide particles;

and forming a silicon dioxide layer on the surface of the silicon carbide particles, etching the silicon dioxide layer, washing with water, and drying.

2. The method for pre-treating silicon carbide particles according to claim 1, wherein the etching conditions are as follows: soaking the mixture for 60 to 180 minutes by adopting 2 to 6mol/L ammonium fluoride aqueous solution.

3. The method for pretreating silicon carbide particles according to claim 1, wherein the drying temperature is 120-250 ℃ and the drying time is 60-180 minutes.

4. The method for pretreating silicon carbide particles according to claim 1, wherein the step of forming a silica layer on the surface of the silicon carbide particles comprises:

and calcining the silicon carbide particles at 1200-1500 ℃ for 30-60 minutes.

5. The method for pretreating silicon carbide particles according to claim 1 or 4, further comprising a step of removing impurities from the surfaces of the silicon carbide particles before the step of forming a silica layer on the surfaces of the silicon carbide particles.

6. The method for pretreating silicon carbide particles according to claim 5, wherein the step of removing impurities from the surfaces of the silicon carbide particles comprises:

and (3) sequentially carrying out alkali washing, acid washing and water washing on the silicon carbide particles, and drying.

7. The method for pretreating silicon carbide particles according to claim 6, wherein, in the step of drying after sequentially subjecting the silicon carbide particles to alkali washing, acid washing and water washing:

the alkali washing is to wash for 30-120 minutes by adopting 1-5 mol/L sodium hydroxide aqueous solution; the pickling step is to clean the steel plate for 30-60 minutes by adopting 10-20% hydrochloric acid solution; the drying temperature is 120-250 ℃, and the drying time is 30-60 minutes.

8. The preparation method of the aluminum matrix composite is characterized by comprising the following steps:

providing silicon carbide particles pretreated by the pretreatment method of any one of claims 1 to 7;

providing aluminum alloy raw material powder, wherein the aluminum alloy raw material powder consists of aluminum powder, aluminum-magnesium intermediate alloy powder, aluminum-copper intermediate alloy powder, aluminum-zirconium intermediate alloy powder, aluminum-yttrium intermediate alloy powder, aluminum-cerium intermediate alloy powder and propyl gallate, the mass content of magnesium in the aluminum alloy raw material powder is 1.5-3.2%, the mass content of copper is 1.0-2.5%, the mass content of zirconium is 0.2-0.5%, the mass content of yttrium is 0.1-0.5%, the mass content of cerium is 0.1-0.5%, the mass content of propyl gallate is 1-2%, and the balance is aluminum;

mechanically stirring and uniformly mixing the aluminum-magnesium intermediate alloy powder, the aluminum-copper intermediate alloy powder, the aluminum-zirconium intermediate alloy powder, the aluminum-yttrium intermediate alloy powder, the aluminum-cerium intermediate alloy powder and part of the aluminum powder, and adding propyl gallate to obtain a first mixture;

performing airflow mixing on the first mixture, the rest aluminum powder and the silicon carbide particles, and then mechanically stirring and uniformly mixing to obtain a second mixture;

and pressing and molding the second mixture, and sintering to obtain the aluminum-based composite material.

9. The method for preparing the aluminum-based composite material according to claim 7, wherein the mass of the aluminum powder in the first mixture is 2 to 5 times of the total mass of the aluminum-magnesium intermediate alloy powder, the aluminum-copper intermediate alloy powder, the aluminum-zirconium intermediate alloy powder, the aluminum-yttrium intermediate alloy powder and the aluminum-cerium intermediate alloy powder.

10. The method for preparing the aluminum-based composite material according to claim 7, wherein the second mixture contains 50 to 70 mass% of silicon carbide.

11. The method for producing an aluminum-based composite material according to claim 7, wherein the pressure of the press molding is 150 to 300 MPa; the sintering conditions are as follows: sintering at 380-600 ℃ for 1-3 hours.

Technical Field

The invention relates to the technical field of composite materials, in particular to a pretreatment method of silicon carbide particles and a preparation method of an aluminum matrix composite material.

Background

The silicon carbide particles have excellent performances such as high modulus, high wear resistance, high strength, low density, high temperature resistance and the like, while the aluminum-based material (mainly aluminum or aluminum alloy) has the advantages of light weight, good thermal conductivity and the like, the silicon carbide particles and the aluminum-based material are compounded, the comprehensive performance of the aluminum-based material can be greatly improved, the higher the content is, the more remarkable the reinforcing effect is, but the problems of poor wettability between the silicon carbide particles and the aluminum powder, uneven distribution of the silicon carbide particles in a matrix, poor interface bonding, harmful interface reaction and the like are amplified along with the increase of the content of the silicon carbide particles, and the application of the silicon carbide particle reinforced aluminum-based composite is greatly limited.

Pretreatment of silicon carbide particles is an important approach to solve the above problems. The silicon carbide particle pretreatment methods which have been reported so far are: high-temperature oxidation, surface coating, acid washing, alkali washing, ultrasonic cleaning and the like. The high-temperature oxidation is to heat the silicon carbide particles to over 1000 ℃ and keep the temperature for a long time to oxidize the surfaces of the silicon carbide particles to generate SiO₂Oxide to improve wettability. However, the method is only suitable for the aluminum matrix composite material with the silicon carbide particle content of below 30 percent, and agglomeration is still easy to occur along with the increase of the silicon carbide particle content in the aluminum matrix composite materialUneven particle distribution, etc. The surface coating is formed by plating a metal layer such as Ni or Cu on the surface of silicon carbide particles by a physical or chemical method to achieve the purpose of improving the wettability between the silicon carbide particles and the aluminum liquid, but the method has high production cost and is difficult to realize large-scale industrial application. The methods of acid washing, alkali washing, ultrasonic cleaning and the like can only remove impurities, organic matters, water and the like adsorbed on the surfaces of the silicon carbide particles to obtain relatively pure silicon carbide particles, but cannot solve the problem of wettability between the silicon carbide particles and aluminum powder.

Disclosure of Invention

Based on this, it is necessary to provide a pretreatment method for silicon carbide particles, and the silicon carbide particles treated by the method have better wettability and interface bonding force with aluminum powder, so that the mass content of the silicon carbide particles in the aluminum matrix composite material can reach more than 50%, even 70%.

A pretreatment method of silicon carbide particles comprises the following steps:

providing silicon carbide particles;

and forming a silicon dioxide layer on the surface of the silicon carbide particles, etching the silicon dioxide layer, washing with water, and drying.

In one embodiment, the etching conditions are: soaking the mixture for 60 to 180 minutes by adopting 2 to 6mol/L ammonium fluoride aqueous solution.

In one embodiment, the drying temperature is 120-250 ℃ and the drying time is 60-180 minutes.

In one embodiment, the step of forming the silicon dioxide layer on the surface of the silicon carbide particles specifically comprises:

and calcining the silicon carbide particles at 1200-1500 ℃ for 30-60 minutes.

In one embodiment, before the step of forming the silicon dioxide layer on the surfaces of the silicon carbide particles, a step of removing impurities from the surfaces of the silicon carbide particles is further included.

In one embodiment, the step of performing surface impurity removal on the silicon carbide particles specifically comprises:

and (3) sequentially carrying out alkali washing, acid washing and water washing on the silicon carbide particles, and drying.

In one embodiment, in the steps of sequentially performing alkali washing, acid washing and water washing on the silicon carbide particles, and drying:

the alkali washing is to wash for 30-120 minutes by adopting 1-5 mol/L sodium hydroxide aqueous solution; the pickling step is to clean the steel plate for 30-60 minutes by adopting 10-20% hydrochloric acid solution; the drying temperature is 120-250 ℃, and the drying time is 30-60 minutes.

In addition, the application also provides a preparation method of the aluminum matrix composite, which comprises the following steps:

providing silicon carbide particles pretreated by any one of the pretreatment methods described above;

providing aluminum alloy raw material powder, wherein the aluminum alloy raw material powder consists of aluminum powder, aluminum-magnesium intermediate alloy powder, aluminum-copper intermediate alloy powder, aluminum-zirconium intermediate alloy powder, aluminum-yttrium intermediate alloy powder, aluminum-cerium intermediate alloy powder and propyl gallate, the mass content of magnesium in the aluminum alloy raw material powder is 1.5-3.2%, the mass content of copper is 1.0-2.5%, the mass content of zirconium is 0.2-0.5%, the mass content of yttrium is 0.1-0.5%, the mass content of cerium is 0.1-0.5%, the mass content of propyl gallate is 1-2%, and the balance is aluminum;

mechanically stirring and uniformly mixing the aluminum-magnesium intermediate alloy powder, the aluminum-copper intermediate alloy powder, the aluminum-zirconium intermediate alloy powder, the aluminum-yttrium intermediate alloy powder, the aluminum-cerium intermediate alloy powder and part of the aluminum powder, and adding the propyl gallate to obtain a first mixture;

performing airflow mixing on the first mixture, the rest aluminum powder and the silicon carbide particles, and then mechanically stirring and uniformly mixing to obtain a second mixture;

and pressing and molding the second mixture, and sintering to obtain the aluminum-based composite material.

In one embodiment, the mass of the aluminum powder in the first mixture is 2 to 5 times of the sum of the masses of the aluminum-magnesium intermediate alloy powder, the aluminum-copper intermediate alloy powder, the aluminum-zirconium intermediate alloy powder, the aluminum-yttrium intermediate alloy powder and the aluminum-cerium intermediate alloy powder.

In one embodiment, the second mixture contains silicon carbide 50-70% by mass.

In one embodiment, the pressure of the compression molding is 150MPa to 300 MPa; the sintering conditions are as follows: sintering at 380-600 ℃ for 1-3 hours.

According to the preparation method of the aluminum matrix composite, the silicon carbide particles form the silicon dioxide layer on the surface in advance, and then are etched to manufacture the surface holes, on one hand, the silicon dioxide layer can act with alloy elements in the aluminum alloy raw material powder to form an interface product, so that the wettability and the interface bonding strength between the silicon carbide particles and the aluminum alloy raw material powder are improved, on the other hand, the surface holes enable the connection performance between the aluminum alloy raw material powder and the silicon carbide particles to be further enhanced through the physical riveting effect, and the interface separation phenomenon caused by the difference of expansion coefficients is reduced, so that the mass content of the silicon carbide particles in the aluminum matrix composite can reach 50% -70%, and the preparation method is simple and is suitable for industrial large-scale production.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The method for preparing an aluminum matrix composite material according to an embodiment includes the following steps S110 to S170:

s110, silicon carbide particles are provided.

The silicon carbide particles are commercially available silicon carbide particles.

Further, the particle size of the silicon carbide particles is 10 to 20 μm.

By selecting the silicon carbide particles with the particle size of 10-20 microns, the silicon carbide particles are beneficial to uniform dispersion in subsequent aluminum alloy raw material powder, and the deformation difficulty during compression molding can be reduced.

And S120, removing impurities on the surfaces of the silicon carbide particles to obtain the silicon carbide particles after the impurities are removed.

In this embodiment, the step of removing impurities from the surface of the silicon carbide particles specifically includes: and (3) sequentially carrying out alkali washing, acid washing and water washing on the silicon carbide particles, and drying to remove impurities such as silicate adsorbed on the surfaces of the silicon carbide particles so as to be more beneficial to the formation of a subsequent silicon dioxide layer.

Further, the alkali washing is to wash for 30-120 minutes by adopting 1-5 mol/L sodium hydroxide aqueous solution; the acid washing is to wash for 30-60 minutes by adopting 10-20% (mass content) of hydrochloric acid solution; the drying temperature is 120-250 ℃ and the drying time is 30-60 minutes.

And S130, forming a silicon dioxide layer on the surface of the silicon carbide particle after impurity removal, etching the silicon dioxide layer, washing with water, and drying.

In this embodiment, step S130 specifically includes: and calcining the silicon carbide particles after impurity removal at 1200-1500 ℃ for 30-60 minutes.

Further, the etching conditions are as follows: soaking the mixture for 60 to 180 minutes by adopting 2 to 6mol/L ammonium fluoride aqueous solution.

After the silicon carbide particles are processed in steps S110 to S130, a silicon dioxide layer with holes is formed on the surface.

It should be noted that if the impurity content of the silicon carbide particles provided in step S110 is low and the influence on the subsequent silicon dioxide layer is low, step S120 may be omitted.

The drying temperature in the step S130 is 120-250 ℃, and the drying time is 60-180 minutes.

S140, providing aluminum alloy raw material powder.

In the present embodiment, the aluminum alloy raw material powder is composed of aluminum powder, aluminum-magnesium intermediate alloy powder, aluminum-copper intermediate alloy powder, aluminum-zirconium intermediate alloy powder, aluminum-yttrium intermediate alloy powder, aluminum-cerium intermediate alloy powder, and propyl gallate, and the mass content of magnesium in the aluminum alloy raw material powder is 1.5% to 3.2%, the mass content of copper is 1.0% to 2.5%, the mass content of zirconium is 0.2% to 0.5%, the mass content of yttrium is 0.1% to 0.5%, the mass content of cerium is 0.1% to 0.5%, the mass content of propyl gallate is 1% to 2%, and the balance is aluminum.

In step S140, the raw material powders are left to stand without being mixed.

S150, mechanically stirring and uniformly mixing the aluminum-magnesium intermediate alloy powder, the aluminum-copper intermediate alloy powder, the aluminum-zirconium intermediate alloy powder, the aluminum-yttrium intermediate alloy powder, the aluminum-cerium intermediate alloy powder and part of aluminum powder, and adding Propyl Gallate (PG) to obtain a first mixture.

The mass of the aluminum powder in the first mixture is 2-5 times of the sum of the mass of the aluminum-magnesium intermediate alloy powder, the mass of the aluminum-copper intermediate alloy powder, the mass of the aluminum-zirconium intermediate alloy powder, the mass of the aluminum-yttrium intermediate alloy powder and the mass of the aluminum-cerium intermediate alloy powder.

It is understood that the mass of the al-mg master alloy powder, the al-cu master alloy powder, the al-zr master alloy powder, the al-y master alloy powder, and the al-ce master alloy powder may be determined according to the mass content of the mg element, the cu element, the zr element, the y element, and the ce element in the al-alloy raw material powder in step S140, and thus the mass of the al powder added in step S150 is determined.

The alloy elements can be enriched at the interface between the silicon carbide particles and the aluminum powder in the subsequent sintering process, wherein magnesium elements and copper elements are easy to react with a silicon dioxide layer on the surface of the silicon carbide particles to form a good interface reactant and improve the interface bonding force, and the addition of zirconium elements, yttrium elements and cerium elements increases the solid solution strengthening effect of the material, and simultaneously, the yttrium elements and the cerium elements can play the roles of deoxidation and dispersion strengthening in the subsequent sintering process, thereby effectively promoting the uniform dispersion of the silicon carbide particles in a matrix.

It is understood that the addition of PG serves to bind and further increase interfacial bonding, and serves to deoxidize during the subsequent sintering process.

And S160, performing airflow mixing on the first mixture, the residual aluminum powder and the silicon carbide particles, and then mechanically stirring and uniformly mixing to obtain a second mixture.

Specifically, the first mixture, the residual aluminum powder and the silicon carbide particles are respectively atomized by nitrogen and output to carry out air flow mixing, so that the silicon carbide particles and the aluminum powder are uniformly mixed, and the agglomeration phenomenon of the silicon carbide particles is prevented.

It is understood that the silicon carbide particles in step S160 are silicon carbide particles processed in steps S110 to S130.

Further, the mass content of the silicon carbide particles in the second mixture is 50-70%.

S170, pressing and forming the second mixture, and sintering to obtain the aluminum matrix composite.

Wherein the pressure of the compression molding is 150 MPa-300 MPa. The sintering conditions are as follows: sintering at 380-600 ℃ for 1-3 hours.

By controlling the sintering temperature and time, the copper element and the magnesium element can more easily break through oxide skin on the surface of the aluminum powder for diffusion, and meanwhile, the silicon dioxide layer on the surface of the silicon carbide particles is more tightly combined with the aluminum powder and alloy elements in a reaction manner, so that the density of the aluminum matrix composite material is effectively improved.

The aluminum matrix composite material prepared by the method has the tensile strength of 200-250 MPa and the linear expansion coefficient of 9-10 at 25-300 ℃ through tests.

The aluminum-based composite material prepared by the method has excellent performance, and can be used in industries such as missile gyroscopes, radar T/R components, satellite frames and the like with high requirements on strength and expansion coefficients.

The following are specific examples.

Example 1

(1) The method comprises the steps of adopting general SiC particles on the market, wherein the size of the particles is 10-20 microns, cleaning the particles for 30 minutes by using 1mol/L NaOH aqueous solution, cleaning the particles for 30 minutes by using 20 wt% hydrochloric acid solution, finally cleaning the particles by using purified water, and baking the particles for 60 minutes in an oven at 180 ℃ to obtain the impurity-removed silicon carbide particles.

(2) Calcining the silicon carbide particles after impurity removal at 1500 ℃ for 60 minutes to obtain an oxide layer with a certain thickness on the surfaces of the SiC particles, and then soaking the silicon carbide particles into 3mol/L NH₄And F, soaking in the aqueous solution for 120 minutes, cleaning with clear water, and baking in an oven at 180 ℃ for 60 minutes to obtain pretreated silicon carbide particles.

(3) Mechanically stirring and uniformly mixing 5g of aluminum-magnesium intermediate alloy powder (50 wt%), 4g of aluminum-copper intermediate alloy powder (50 wt%), 1g of aluminum-zirconium intermediate alloy powder (50 wt%), 1g of aluminum-yttrium intermediate alloy powder (50 wt%), 0.8g of aluminum-cerium intermediate alloy powder (50 wt%) and 25g of aluminum powder, and adding 1g of propyl gallate to obtain a first mixture.

(4) And atomizing the first mixture, 62.2g of aluminum powder and 100g of silicon carbide particles by using nitrogen respectively, then carrying out airflow mixing, and mechanically stirring and uniformly mixing to obtain a second mixture.

(5) And pressing and molding the second mixture at 300MPa, and sintering at 600 ℃ for 2h to obtain the aluminum-based composite material.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the embodiment 1 is 210MPa, and the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 9.8.

Example 2

Example 2 is substantially the same as example 1 except that step (1) is omitted from example 2.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the embodiment 2 is 201MPa, and the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 10.

As can be seen from comparison between example 1 and example 2, the aluminum matrix composite material SiC particles obtained by the preparation method of the present application are uniformly dispersed and have good interface bonding, but the tensile strength of the aluminum matrix composite material is slightly reduced due to the presence of impurities on the surface of the SiC particles.

Comparative example 1

Comparative example 1 is substantially the same as example 1 except that comparative example 1 omits step (2).

Through detection, the tensile strength of the aluminum matrix composite material prepared in the comparative example 1 is 169MPa, and the linear expansion coefficient at 25-300 ℃ is 10.3.

By comparing the example 1 with the comparative example 1, the mechanical embedding effect of the aluminum powder and the surface of the SiC particle is improved by the microetching pore-forming technology for the surface of the SiC particle, and the reaction specific surface area of SiC and Al can be further ensured by the surface oxidation process, so that the step (2) is omitted, and the adverse effect on the material performance and the thermal expansion performance is avoided.

Comparative example 2

Comparative example 2 is substantially the same as example 1 except that comparative example 2 is mixed by mechanical stirring directly in step (4) without mixing with a gas flow and then mixing with mechanical stirring.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the comparative example 2 is 193MPa, the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 10.1, and the agglomeration of silicon carbide particles is found through the microstructure.

Comparative example 3

Comparative example 3 is substantially the same as example 1 except that in comparative example 3, the amount of addition of the aluminum-copper master alloy powder in step (3) was 1g, and the amount of addition of the aluminum powder in step (4) was 65.2 g.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the comparative example 3 is 189.6MPa, and the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 10.2.

By comparing the embodiment 1 with the comparative example 3, the copper element can improve the wettability of the Al powder, and simultaneously improve the performance of the matrix through alloying to influence the mechanical property of the material, so that the strengthening effect of the whole matrix is reduced due to the reduction of the content of the copper element, and the dispersed precipitated phase in the heat treatment is reduced.

Example 3

(1) The method comprises the steps of adopting general SiC particles on the market, wherein the size of the particles is 10-20 microns, cleaning the particles for 120 minutes by using a 5mol/L NaOH aqueous solution, cleaning the particles for 60 minutes by using a 10 wt% hydrochloric acid solution, finally cleaning the particles by using purified water, and baking the particles in an oven at 250 ℃ for 30 minutes to obtain the impurity-removed silicon carbide particles.

(2) Calcining the silicon carbide particles after impurity removal at 1200 ℃ for 30 minutes to obtain an oxide layer with a certain thickness on the surfaces of the SiC particles, and then soaking the silicon carbide particles in 6mol/L NH₄And F, soaking in the aqueous solution for 60 minutes, then washing with clean water, and baking in an oven at 120 ℃ for 180 minutes to obtain pretreated silicon carbide particles.

(5) 3g of aluminum-magnesium intermediate alloy powder (50 wt%), 2g of aluminum-copper intermediate alloy powder (50 wt%), 0.4g of aluminum-zirconium intermediate alloy powder (50 wt%), 0.2g of aluminum-yttrium intermediate alloy powder (50 wt%), 0.2g of aluminum-cerium intermediate alloy powder (50 wt%) and 29g of aluminum powder are mechanically stirred and mixed uniformly, and then 2g of propyl gallate is added to obtain a first mixture.

(6) And respectively atomizing the first mixture, 63.2g of aluminum powder and 233g of silicon carbide particles by using nitrogen, outputting, mixing by air flow, and mechanically stirring and uniformly mixing to obtain a second mixture.

(5) And pressing and molding the second mixture at 150MPa, and sintering at 380 ℃ for 3h to obtain the aluminum-based composite material.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the embodiment 3 is 250MPa, and the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 9.1.

Example 4

(1) The method comprises the steps of adopting general SiC particles on the market, wherein the size of the particles is 10-20 microns, washing the particles for 60 minutes by using a 5mol/L NaOH aqueous solution, then washing the particles for 60 minutes by using a 10 wt% hydrochloric acid solution, finally washing the particles by using purified water, and then baking the particles for 50 minutes in an oven at 200 ℃ to obtain the impurity-removed silicon carbide particles.

(2) Calcining the silicon carbide particles after impurity removal at 1200 ℃ for 45 minutes to obtain an oxide layer with a certain thickness on the surfaces of the SiC particles, and then soaking the silicon carbide particles into 2mol/L NH₄And F, soaking in the aqueous solution for 180 minutes, cleaning with clear water, and baking in an oven at 250 ℃ for 60 minutes to obtain pretreated silicon carbide particles.

(7) Mechanically stirring and uniformly mixing 6.4g of aluminum-magnesium intermediate alloy powder (50 wt% in mass fraction), 5g of aluminum-copper intermediate alloy powder (50 wt% in mass fraction), 1g of aluminum-zirconium intermediate alloy powder (50 wt% in mass fraction), 1g of aluminum-yttrium intermediate alloy powder (50 wt% in mass fraction), 1g of aluminum-cerium intermediate alloy powder (50 wt% in mass fraction) and 28.8g of aluminum powder, and adding 1g of propyl gallate to obtain a first mixture.

(8) And respectively atomizing the first mixture, 55.8g of aluminum powder and 150g of silicon carbide particles by using nitrogen, outputting, mixing with air flow, and mechanically stirring and uniformly mixing to obtain a second mixture.

(5) And pressing and molding the second mixture at 200MPa, and sintering at 600 ℃ for 1h to obtain the aluminum-based composite material.

Through detection, the tensile strength of the aluminum matrix composite material prepared in the embodiment 3 is 235MPa, and the linear expansion coefficient of the aluminum matrix composite material at 25-300 ℃ is 9.4.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.