Silicon carbide particle reinforced aluminum-based composite material and preparation method thereof

Abstract

The invention discloses a silicon carbide particle reinforced aluminum-based composite material and a preparation method thereof.The preparation method of the silicon carbide particle reinforced aluminum-based composite material comprises the steps that after a grain refiner and an alterant are added into a matrix aluminum alloy melt, argon is introduced for refining and degassing, and the aluminum alloy melt is obtained; and under the vacuum condition, activated silicon carbide particles are gradually added into the molten aluminum alloy, a composite reaction is conducted, and the silicon carbide particle reinforced aluminum matrix composite is obtained. According to the embodiment, the silicon carbide particle reinforced phase is introduced into the aluminum alloy matrix, in the obtained silicon carbide particle reinforced aluminum matrix composite, silicon carbide particles and the matrix can be well combined and dispersed, the porosity is low, products such as cast ingots prepared from the silicon carbide particle reinforced aluminum matrix composite have high strength, and the silicon carbide particle reinforced aluminum matrix composite can be applied to the field with high requirements for material performance; and the application range of the aluminum-based composite material is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a silicon carbide particle reinforced aluminum-based composite material and a preparation method thereof. Background Art

[0002] SiC (silicon carbide) particles have high strength, high hardness and excellent wear resistance. Applying them to aluminum-based alloy materials can improve the performance of aluminum-based materials. However, when applying silicon carbide to aluminum-based alloy materials using existing methods, problems such as silicon carbide particles not combining with the matrix material, easy to fall off, silicon carbide particles agglomerating, excessive pores, poor porosity, and excessive oxide inclusions will occur. These problems make it difficult to apply the prepared composite materials to aerospace, automotive industry, electronic packaging and other fields, especially to brake discs of rail vehicles and passenger vehicles, substrates of chip products and other fields with high requirements on material performance. Its application is even more limited.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a silicon carbide particle reinforced aluminum-based composite material and a preparation method thereof, so as to improve the uniformity of the dispersion of silicon carbide particles in a matrix and the bonding strength with the matrix.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, comprising:

[0007] After adding a grain refiner and a modifier into a base aluminum alloy melt, argon gas is introduced for refining and degassing to obtain an aluminum alloy melt;

[0008] Under vacuum conditions, activated silicon carbide particles are gradually added to the aluminum alloy melt and a composite reaction is carried out to obtain a silicon carbide particle reinforced aluminum-based composite material.

[0009] In an optional embodiment, the method for activating the silicon carbide particles comprises: keeping the silicon carbide particles warm under aerobic conditions for 5 hours to 24 hours at a temperature of 900° C. to 1600° C.

[0010] In an optional embodiment, the mass fraction of silicon carbide particles in the composite material melt is less than 40%.

[0011] In an optional embodiment, the particle size of the silicon carbide particles is 3 to 50 μm, and the aspect ratio is less than 4:1; and / or the purity of the silicon carbide particles is ≥ 90%

[0012] In an optional embodiment, the grain refiner is AlTi5B1, and the mass ratio of the grain refiner to the matrix aluminum alloy melt is 0.5% to 1.5%.

[0013] In an optional embodiment, the modifier is Al-Sr10, and the mass ratio of the modifier to the matrix aluminum alloy melt is 0.1% to 0.3%.

[0014] In an optional embodiment, when the grain refiner and the modifier are added, the temperature of the matrix aluminum alloy melt is 720°C to 745°C.

[0015] In an optional embodiment, the temperature of the composite reaction step is 580°C to 730°C, and the time is 30min to 120min;

[0016] And / or, the composite reaction step is accompanied by stirring, and the stirring speed is ≥300r / min;

[0017] And / or, in the composite reaction step, the adding rate of activated silicon carbide particles is ≤4 kg / min.

[0018] In an optional embodiment, the vacuum degree of the vacuum condition is ≤100Pa.

[0019] In a second aspect, the present invention provides a silicon carbide particle reinforced aluminum-based composite material prepared by the method described in any one of the aforementioned embodiments.

[0020] The present invention has the following beneficial effects:

[0021] In this embodiment, silicon carbide particle reinforcement phase is introduced into the aluminum alloy matrix to obtain a silicon carbide particle reinforced aluminum-based composite material. The silicon carbide particles and the matrix can be well combined and dispersed, the porosity is low, and products such as ingots prepared therefrom have high strength and can be used in fields with high requirements on material properties, which is conducive to expanding the application range of aluminum-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a 100-fold metallographic image of the composite ingot sample corresponding to Example 1;

[0024] Figure 2 This is a 200-fold metallographic image of the composite ingot sample corresponding to Example 1;

[0025] Figure 3 500 times metallographic image of the composite ingot sample corresponding to Example 1;

[0026] Figure 4 It is a 100-fold metallographic image of the composite ingot sample corresponding to Comparative Example 3;

[0027] Figure 5 This is a 100-fold metallographic image of the composite ingot sample corresponding to Comparative Example 4. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0029] An embodiment of the present invention provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, comprising:

[0030] After adding a grain refiner and a modifier into a base aluminum alloy melt, argon gas is introduced for refining and degassing to obtain an aluminum alloy melt;

[0031] Under vacuum conditions, activated silicon carbide particles are gradually added to the aluminum alloy melt and a composite reaction is carried out to obtain a silicon carbide particle reinforced aluminum-based composite material.

[0032] In this embodiment, silicon carbide particle reinforcement phase is introduced into the aluminum alloy matrix to obtain a silicon carbide particle reinforced aluminum-based composite material. The silicon carbide particles and the matrix can be well combined and dispersed, the porosity is low, and products such as ingots prepared therefrom have high strength and can be used in fields with high requirements on material properties, which is conducive to expanding the application range of aluminum-based composite materials.

[0033] In the existing silicon carbide particle reinforced materials, the bonding force between silicon carbide particles and the matrix is ​​small and easy to fall off. Therefore, in this application, activated silicon carbide particles are added to the aluminum alloy melt. After the silicon carbide particles are activated, their surfaces can react with the aluminum alloy melt, so that chemical bonds are formed between silicon and aluminum or other elements in the aluminum alloy melt, which is conducive to improving the bonding force between the silicon carbide particles and the matrix. Furthermore, in this application, the activated silicon carbide particles are gradually added to the aluminum alloy melt to avoid adding a large amount of silicon carbide particles at the same time, which is conducive to the silicon carbide particles being able to be more evenly dispersed in the matrix, and then it is also conducive to the silicon carbide particles and The matrix fully react, and it is more conducive to further reducing the number of silicon carbide particles with weak bonding force with the matrix.

[0034] It should be noted that, in the present application, the matrix aluminum alloy melt can be obtained by melting existing aluminum alloys, and specifically, aluminum-silicon and aluminum-copper casting aluminum alloys can be selected.

[0035] In an optional embodiment, the method for activating the silicon carbide particles comprises: keeping the silicon carbide particles warm under aerobic conditions for 5 hours to 24 hours at a temperature of 900° C. to 1600° C.

[0036] Among them, the insulation temperature can be 900℃~1600℃, specifically 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, 1600℃ or any value between 900℃ and 1600℃; the insulation time can be 7h, 9h, 13h, 17h, 20h, 24h or any value between 5h and 24h.

[0037] Under the above conditions, the silicon carbide particles can be fully activated. It should be noted that the silicon carbide particles can be stirred or turned during the activation process to facilitate full and uniform activation of the silicon carbide particles while avoiding adhesion between the particles.

[0038] In an optional embodiment, the mass fraction of silicon carbide particles in the composite material melt is less than 40%.

[0039] As the proportion of silicon carbide particles increases, the performance of products such as ingots made of silicon carbide particle-reinforced aluminum-based composite materials, such as strength, will first increase and then decrease. Therefore, the proportion of silicon carbide particles should not be too high.

[0040] In an optional embodiment, the silicon carbide particles have a particle size of 3 to 50 μm and an aspect ratio of <4:1;

[0041] And / or, the purity of the silicon carbide particles is ≥90%.

[0042] The smaller the particle size of silicon carbide particles, the better their uniform dispersion in the melt. However, if the particles are too small, the fluidity of the melt will be reduced, which is not conducive to subsequent production. Therefore, the particle size of silicon carbide particles should be maintained between 3 and 50 μm. In addition, spherical silicon carbide particles have better fluidity, which is conducive to controlling the feeding rate. At the same time, spherical silicon carbide particles are conducive to reducing the cracking of products such as ingots prepared from silicon carbide particle-reinforced aluminum-based composite materials.

[0043] In an optional embodiment, the grain refiner is AlTi5B1, and the mass ratio of the grain refiner to the base aluminum alloy melt is 0.5% to 1.5%, which is specifically determined according to the Ti content in the base aluminum alloy, and the mass fraction of Ti in the alloy is ultimately controlled in the range of 0.7 to 1.5%.

[0044] In an optional embodiment, the modifier is Al-Sr10, and the mass ratio of the modifier to the matrix aluminum alloy melt is 0.1% to 0.3%.

[0045] In an optional embodiment, when grain refiners and modifiers are added, the temperature of the base aluminum alloy melt is 720°C to 745°C, specifically 720°C, 725°C, 730°C, 735°C, 740°C, 745°C or any value between 720°C and 745°C.

[0046] Adding grain refiners and modifiers is beneficial to refining the grains of products such as ingots made of silicon carbide particle reinforced aluminum-based composite materials and improving their performance; in addition, the reaction between the grain refiners and modifiers and the melt is more favorable within the range of 720°C to 745°C.

[0047] In an optional embodiment, the temperature of the composite reaction step is 580°C to 730°C, specifically 580°C, 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 730°C or any value between 580°C and 730°C; the time is 30min to 120min, specifically 30min, 60min, 90min, 120min or any value between 30min and 120min;

[0048] And / or, the composite reaction step is accompanied by stirring, and the stirring speed is ≥300r / min;

[0049] And / or, in the composite reaction step, the addition rate of the activated silicon carbide particles is ≤4kg / min, specifically, it can be 4kg / min, 3kg / min, 2kg / min, 1kg / min, 0.5kg / min or any value less than 4kg / min. The lower the addition rate, the more conducive it is to the uniform dispersion of the activated silicon carbide particles. However, too low an addition rate will lead to a decrease in production efficiency. Therefore, in some embodiments, the addition rate of the activated silicon carbide particles can be 1kg / min-4kg / min, and the addition method of the activated silicon carbide particles can be continuous uninterrupted addition or intermittent addition.

[0050] In an optional embodiment, the vacuum degree of the vacuum condition is ≤1000Pa, which reduces the entry of gas.

[0051] An embodiment of the present invention further provides a silicon carbide particle reinforced aluminum-based composite material, which is prepared by the method described in any one of the aforementioned embodiments.

[0052] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0053] Example 1

[0054] This embodiment provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, comprising:

[0055] Step 1, selecting silicon carbide particles with a particle size of 3 to 20 μm, an aspect ratio of less than 4:1, and a purity of 99 wt%; heating the silicon carbide particles to 1100° C. in air, and keeping the temperature for 20 hours for full activation, and turning the silicon carbide particles during the heat preservation process to ensure uniform activation of the SIC;

[0056] Step 2, after melting and deslagging the base aluminum alloy ingot (AlSi9Mg), clean up the scum on the liquid surface, add a grain refiner Al-(5wt%)Ti-(1wt%)B and a modifier Al-(10wt%)Sr into the base aluminum alloy melt at 735°C, and introduce high-purity argon (purity ≥99.999%) for refining and degassing to obtain an aluminum alloy melt, wherein the mass ratio of the grain refiner to the base aluminum alloy melt is 0.6%; the mass ratio of the modifier to the base aluminum alloy melt is 0.15%;

[0057] Step 3, the aluminum alloy melt is sent into a vacuum furnace, and in a vacuum environment with a vacuum degree of ≤20Pa, a stirring rod is inserted for stirring, and the stirring rod speed is 400r / min. During the stirring process, activated silicon carbide particles are added into the aluminum alloy melt at 660°C for composite reaction. The composite reaction time (calculated from the beginning of adding silicon carbide particles) is 90min, and the addition rate of activated silicon carbide particles is 2kg / min.

[0058] Step 4: Clean the scum on the liquid surface and the crucible wall to obtain a clean and qualified silicon carbide particle reinforced aluminum matrix composite material. The metallographic image is as follows: Figure 1-3 As shown, the mass fraction of silicon carbide particles in the composite material melt is 20%.

[0059] Example 2

[0060] This embodiment provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, comprising:

[0061] Step 1, selecting silicon carbide particles with a particle size of 20 to 40 μm, an aspect ratio of less than 4:1, and a purity of 99%; heating the silicon carbide particles to 1000° C. in air, and keeping the temperature for 24 hours for full activation, and turning the silicon carbide particles during the heat preservation process to ensure uniform activation of the SIC;

[0062] Step 2, after melting and deslagging the base aluminum alloy ingot (AlSi10Mg), clean up the scum on the liquid surface, add a grain refiner Al-(5wt%)Ti-(1wt%)B and a modifier Al-(10wt%)Sr into the base aluminum alloy melt at 720°C, and introduce high-purity argon (purity ≥99.999%) for refining and degassing to obtain an aluminum alloy melt, wherein the mass ratio of the grain refiner to the base aluminum alloy melt is 1.2%; the mass ratio of the modifier to the base aluminum alloy melt is 0.15%;

[0063] Step 3, the aluminum alloy melt is sent into a vacuum furnace, and in a vacuum environment with a vacuum degree of ≤40Pa, a stirring rod is inserted for stirring, and the stirring rod speed is 500r / min. During the stirring process, activated silicon carbide particles are added into the aluminum alloy melt at 610°C for composite reaction. The composite reaction time (calculated from the beginning of adding silicon carbide particles) is 120min, and the addition rate of activated silicon carbide particles is 1kg / min.

[0064] Step 4: clean the scum on the liquid surface and the crucible wall to obtain a clean and qualified silicon carbide particle reinforced aluminum-based composite material, wherein the mass fraction of silicon carbide particles in the composite material melt is 10%.

[0065] Comparative Example 1

[0066] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 only in that in step 1, the silicon carbide particles are heated to 800° C. in air and kept warm.

[0067] Comparative Example 2

[0068] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 only in that the insulation time in step 1 is 4 hours.

[0069] Comparative Example 3

[0070] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 only in that the composite reaction temperature in step 3 is 560°C.

[0071] Comparative Example 4

[0072] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 only in that in step 3, the activated silicon carbide particles are quickly added to the melt within 10 seconds and the stirring rate is increased to 600 r / min.

[0073] Comparative Example 5

[0074] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 mainly in that silicon carbide particles are first added for composite reaction, and then a grain refiner and a modifier are added after the composite reaction is completed.

[0075] Comparative Example 6

[0076] This comparative example provides a method for preparing a silicon carbide particle reinforced aluminum-based composite material, which is different from Example 1 only in that the mass ratio of the grain refiner to the matrix aluminum alloy melt in step 2 is 0.2%.

[0077] The above embodiments are put into practical operation, and the test results are as follows:

[0078] Comparative Example 1: Since the SIC activation temperature was not high enough, the SIC particles did not undergo activation reaction and could not be combined with the aluminum matrix, resulting in batching failure.

[0079] Comparative Example 2: SIC activation was insufficient, a large amount of gas was released during the batching process, the porosity of the aluminum ceramic melt exceeded the standard, the SIC particles were severely agglomerated, and the material was unqualified;

[0080] Comparative Example 3: The aluminum liquid temperature is too low, the aluminum liquid has too much solid phase, the stirring resistance is extremely large, the stirring speed cannot be increased (the stirring rod will be damaged if the stirring resistance is too large at a high speed), the SIC cannot be evenly distributed, and the agglomeration is serious. The metallographic image of the ingot sample is as follows Figure 4 As shown;

[0081] Comparative Example 4: The SIC addition flow rate is too large, the stirring system cannot mix the SIC in time, and the SIC particles are partially agglomerated. The metallographic image of the ingot sample is as follows: Figure 5 As shown;

[0082] Comparative Example 5: SIC particles are first added to the mixture, and then a grain refiner and a modifier are added and argon is introduced to perform melt refining. Since the SIC particles are infusible in the aluminum ceramic melt, during the argon refining process, the SIC particles will also lose their wettability and float on the surface. They are cleaned out of the aluminum melt as inclusions, and the batching fails.

[0083] Comparative Example 6: Too little grain refiner was added, resulting in huge clusters of aluminum alloy crystals and SIC particles, poor processability of aluminum liquid, and difficulty in forming castings.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicon carbide particle reinforced aluminum-based composite material, characterized in that: include: After adding a grain refiner and a modifier into a base aluminum alloy melt, argon gas is introduced for refining and degassing to obtain an aluminum alloy melt; Under vacuum conditions, activated silicon carbide particles are gradually added to the aluminum alloy melt and a composite reaction is carried out to obtain a silicon carbide particle reinforced aluminum-based composite material.

2. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The activation method of the silicon carbide particles comprises: keeping the silicon carbide particles warm under aerobic conditions for 5 hours to 24 hours at a temperature of 900° C. to 1600° C.

3. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The mass fraction of silicon carbide particles in the melt of the composite material is less than 40%.

4. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The silicon carbide particles have a particle size of 3 to 50 μm and an aspect ratio of less than 4:1; And / or, the purity of the silicon carbide particles is ≥90%.

5. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The grain refiner is AlTi5B1, and the mass ratio of the grain refiner to the matrix aluminum alloy is 0.4% to 1.5%.

6. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The modifier is Al-Sr10, and the mass ratio of the modifier to the matrix aluminum alloy melt is 0.1% to 0.3%.

7. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: When the grain refiner and modifier are added, the temperature of the matrix aluminum alloy melt is 720°C to 745°C.

8. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The temperature of the composite reaction step is 580°C to 730°C, and the time is 30min to 120min; And / or, the composite reaction step is accompanied by stirring, and the stirring speed is ≥300r / min; And / or, in the composite reaction step, the adding rate of activated silicon carbide particles is ≤4 kg / min.

9. The method for preparing the silicon carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The vacuum degree of the vacuum condition is ≤100Pa.

10. A silicon carbide particle reinforced aluminum matrix composite material, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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