Spherical SiC / Al-Si composite powder as well as preparation method and application thereof

Abstract

The invention relates to spherical SiC / Al-Si composite powder as well as a preparation method and application thereof, and belongs to the technical field of non-metal-containing alloys. The preparation method of the spherical SiC / Al-Si composite powder comprises the following steps that S1, spherical Al-Si pre-alloyed powder and hydrocarbon compound gas (including at least one of alkane gas, olefin gas and alkyne gas) are subjected to a carbonization reaction for 1-10 h at the temperature of 400-700 DEG C, and carbon-coated spherical Al-Si pre-alloyed powder is obtained; and S2, the carbon-coated spherical Al-Si pre-alloyed powder obtained in the step S1 is subjected to an in-situ reaction for 0.5-10 h at the temperature of 750-1000 DEG C in the inert gas atmosphere, and the spherical SiC / Al-Si composite powder is obtained. The spherical SiC / Al-Si composite powder prepared through the preparation method has good fluidity, the content of SiC in the spherical SiC / Al-Si composite powder is controllable, and the interface bonding strength of the spherical SiC / Al-Si composite powder and an Al matrix is high.

Description

Technical Field

[0001] The invention relates to the technical field of alloys containing non-metals, and in particular to a spherical SiC / Al-Si composite powder and a preparation method and application thereof. Background Art

[0002] SiC reinforced Al-based composites are widely used in aviation, aerospace, automobile, military and consumer electronics fields due to their high thermal conductivity, low thermal expansion coefficient, high strength, high wear resistance, low density and low cost. At present, the preparation methods of SiC / Al-based composites are mainly divided into liquid-solid molding and solid-solid molding; among them, the liquid-solid molding method mainly refers to casting (stirring casting, extrusion casting, etc.) and infiltration (pressureless infiltration, pressure infiltration) processes, by adding SiC particles to molten Al alloy melt or infiltrating Al alloy melt into SiC preform skeleton for consolidation molding; while the solid-solid molding method mainly refers to powder metallurgy process, including spark plasma sintering, hot pressing sintering, hot isostatic pressing, powder hot extrusion, injection molding, 3D printing, etc., Al alloy powder and SiC powder are mixed and molded by a mixer or a ball mill.

[0003] It can be seen that both the liquid-solid forming method and the solid-solid forming method adopt the technical route of the external addition method, that is, adding SiC particles to the Al alloy melt or Al alloy powder for compounding, and then consolidation forming. However, since SiC ceramic particles are hard and brittle materials with a hardness close to 30GPa, their morphology is generally irregular and angular, and it is difficult to spheroidize them through cold shaping or high-temperature plasma. Irregular SiC particles will cause stress concentration in the composite material during service, thereby increasing the risk of fracture failure. In addition, SiC ceramic particles have poor wettability with Al melt, and it is difficult to achieve metallurgical bonding. Therefore, it is often necessary to modify the surface of SiC particles to improve the interface bonding strength. Then the surface modification method is bound to increase the cost and introduce unfavorable phases such as impurities, thereby deteriorating the thermodynamic properties of SiC / Al-based composites. Moreover, for processes such as powder injection molding and 3D printing, the morphology and fluidity of the powder are required to be high, and the powder is often required to be spherical and have a certain fluidity; while the mixed powder obtained by mixing element powders has poor fluidity. Even though mechanical ball milling can improve the fluidity and uniformity of the mixed powder, the improvement effect is not ideal, and it is difficult to improve the irregular morphology of SiC particles and the poor bonding between the Al and SiC interface. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a spherical SiC / Al-Si composite powder and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a method for preparing a spherical SiC / Al-Si composite powder, comprising the following steps:

[0007] S1, carbonizing the spherical Al-Si pre-alloyed powder and hydrocarbon compound gas at 400-700° C. for 1-10 hours to obtain carbon-coated spherical Al-Si pre-alloyed powder;

[0008] S2, reacting the carbon-coated spherical Al-Si pre-alloyed powder in S1 in situ at 750-1000° C. in an inert gas atmosphere for 0.5-10 h to obtain a spherical SiC / Al-Si composite powder;

[0009] The hydrocarbon compound gas in S1 includes at least one of alkane gas, olefin gas and alkyne gas.

[0010] The present invention combines spherical Al-Si pre-alloyed powder and hydrocarbon compound gas, uses hydrocarbon compound gas as a carbon source, first forms a carbon coating layer on the surface of the spherical Al-Si pre-alloyed powder by an in-situ vapor deposition method, and then obtains a spherical SiC / Al-Si composite powder with good fluidity through an in-situ reaction between Al, Si and C. The SiC content in the spherical SiC / Al-Si composite powder is controllable, the particles are fine and the morphology is nearly spherical, and the interface bonding strength with the Al matrix is ​​high. In addition, compared with conventional carbon sources such as graphite powder or phenolic resin, the present invention uses hydrocarbon compound gas as a carbon source and combines in-situ vapor deposition, which can not only improve the uniform distribution of carbon, but also effectively prevent powder agglomeration.

[0011] At the same time, the study found that when the temperature of the carburization reaction in step S1 is too low, the hydrocarbon compound gas cannot be cracked into carbon, and a carbon coating layer cannot be formed on the surface of the spherical Al-Si pre-alloyed powder; when the temperature of the carburization reaction is too high, the spherical Al-Si pre-alloyed powder whose surface is not covered with a carbon layer in time will melt and agglomerate. In addition, the temperature and time of the in-situ reaction in step S2 jointly affect the size of the SiC particles. The higher the temperature and the longer the time of the in-situ reaction, the more conducive it is to increase the size of the SiC particles; but when the temperature exceeds 1000°C, the spherical SiC / Al-Si composite powder will melt and it will be difficult to maintain a spherical shape.

[0012] The spherical Al-Si pre-alloyed powder refers to spherical aluminum-silicon alloy particles, which can be obtained by breaking liquid aluminum-silicon alloy into fine droplets and solidifying them by an aerosol method. For details, please refer to CN110904368A (an aluminum-silicon electronic packaging material and its preparation method).

[0013] Optionally, the temperature of the carbonization reaction in S1 can be any one of 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, or any two of the range values, and the time can be any one of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, or any two of the range values.

[0014] Optionally, the temperature of the in-situ reaction in S2 can be any one of 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C or any two of the range values, and the time can be any one of 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or any two of the range values.

[0015] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the mass volume ratio of the spherical Al-Si pre-alloyed powder to the hydrocarbon compound gas g / mL=(100-1000):(100-500). Optionally, the mass volume ratio of the spherical Al-Si pre-alloyed powder to the hydrocarbon compound gas g / mL can be specifically 100:100, 200:150, 300:200, 400:250, 500:300, 600:350, 700:400, 800:450, 900:500, 1000:500.

[0016] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the particle size D of the spherical Al-Si pre-alloyed powder is 50 ≤60 μm, preferably 1 to 60 μm. Optionally, the particle size D of the spherical Al-Si pre-alloyed powder is 50 Specifically, the range value is any one or any two of 1μm, 5μm, 10μm, 15μm, 20μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, and 60μm. Studies have found that the spherical Al-Si pre-alloy powder in the above particle size range can better prevent silicon from agglomerating to form coarse silicon particles during the in-situ reaction, thereby making the in-situ reaction more complete.

[0017] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the spherical Al-Si pre-alloyed powder is mainly composed of Al and Si, wherein the mass content of Si is 5wt.% to 60wt.%. Optionally, the mass content of Si in the spherical Al-Si pre-alloyed powder can be any one of 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, 60wt.%, or any two of the range values.

[0018] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the mass content of carbon in the carbon-coated spherical Al-Si pre-alloyed powder in S1 is 1wt.% to 30wt.%. Optionally, the mass content of carbon in the carbon-coated spherical Al-Si pre-alloyed powder can be any one of 1wt.%, 2wt.%, 4wt.%, 6wt.%, 8wt.%, 10wt.%, 12wt.%, 14wt.%, 16wt.%, 18wt.%, 20wt.%, 22wt.%, 24wt.%, 26wt.%, 28wt.%, 30wt.%, or any two of the range values. The mass content of carbon in the carbon-coated spherical Al-Si pre-alloyed powder can be measured according to the standard GB / T 14265-2017.

[0019] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the mass content of SiC in the spherical SiC / Al-Si composite powder in S2 is 1wt.% to 30wt.%. Optionally, the mass content of SiC in the spherical SiC / Al-Si composite powder can be any one of 1wt.%, 2wt.%, 4wt.%, 6wt.%, 8wt.%, 10wt.%, 12wt.%, 14wt.%, 16wt.%, 18wt.%, 20wt.%, 22wt.%, 24wt.%, 26wt.%, 28wt.%, 30wt.%, or any two of the range values. The mass content of SiC in the spherical SiC / Al-Si composite powder can be measured according to the standard GB / T 3045-2017.

[0020] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, the alkane gas is at least one of methane, ethane and propane;

[0021] And / or, the olefin gas is at least one of ethylene, propylene and butene;

[0022] And / or, the alkyne gas is at least one of acetylene and propyne.

[0023] As a preferred embodiment of the method for preparing the spherical SiC / Al-Si composite powder of the present invention, step S1 is specifically as follows: placing the spherical Al-Si pre-alloyed powder in an atmosphere rotary tube furnace or a gas fluidized bed, and introducing hydrocarbon compound gas, and carbonizing at 400-700°C for 1-10 hours to obtain carbon-coated spherical Al-Si pre-alloyed powder. The main function of the atmosphere rotary tube furnace or the gas fluidized bed is to make the powder flow during the carbonization reaction, so as to better achieve uniform carbon coating.

[0024] In a second aspect, the present invention provides a method for preparing the spherical SiC / Al-Si composite powder obtained by the above preparation method.

[0025] In a third aspect, the present invention provides the use of the spherical SiC / Al-Si composite powder in preparing a radio frequency receiver packaging housing, a radar circuit housing or an engine piston.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The invention combines spherical Al-Si pre-alloyed powder and hydrocarbon compound gas, takes the hydrocarbon compound gas as a carbon source, forms a carbon coating layer on the surface of the spherical Al-Si pre-alloyed powder by an in-situ vapor deposition method, and then obtains a spherical SiC / Al-Si composite powder with good fluidity through an in-situ reaction among Al, Si and C. The SiC content in the spherical SiC / Al-Si composite powder is controllable, the particles are fine and the morphology is nearly spherical, and the interface bonding strength with the Al matrix is ​​high. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the reaction device of the present invention;

[0029] Figure 2 The local SEM image and element surface distribution map of the spherical SiC / Al-Si composite powder in Example 1;

[0030] Figure 3 1 is a SEM image of the spherical Al-Si pre-alloyed powder and the carbon-coated spherical Al-Si pre-alloyed powder in Example 1;

[0031] Figure 4 2. The microstructure diagram of the spherical Al-Si pre-alloyed powder and the spherical SiC / Al-Si composite powder in Example 1. DETAILED DESCRIPTION

[0032] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0033] Unless otherwise specified, other materials, reagents, etc. used in the examples can be obtained from commercial sources.

[0034] Example 1

[0035] The present invention provides a method for preparing spherical SiC / Al-Si composite powder, comprising the following steps:

[0036] S1. A spherical Al-Si pre-alloy powder (denoted as Al-12Si, i.e., Al content is 88 wt.%, Si content is 12 wt.%; particle size D) is obtained by gas atomization method (for details, refer to CN110904368A) 50 =20 μm);

[0037] S2, 500g of the spherical Al-Si pre-alloyed powder in S1 is placed in a rotary tube furnace (such as Figure 1 ) and introduced acetylene gas (gas flow rate of 600 mL / min), then heated to 600°C in a rotary tube furnace at a heating rate of 10°C / min for 2 h to obtain a carbon-coated spherical Al-Si pre-alloyed powder (denoted as Al-12Si-5C, i.e., the mass content of carbon therein is 5 wt.%);

[0038] S3. Heat 500 g of the carbon-coated spherical Al-Si pre-alloyed powder in S2 to 800° C. in an argon atmosphere and keep it for 1 h to obtain a spherical SiC / Al-Si composite powder (denoted as Al-7Si-5SiC, i.e., the mass content of SiC is 5 wt.%).

[0039] Figure 2 a is a local SEM image of the spherical SiC / Al-Si composite powder, b is the surface distribution map of the Al element, c is the surface distribution map of the Si element, and d is the surface distribution map of the C element; according to Figure 2 It can be seen that the in-situ synthesized SiC particles are small, nearly spherical in shape, and have good interface bonding with the Al matrix without obvious cracks.

[0040] Figure 3 a and c correspond to the SEM images of spherical Al-Si pre-alloyed powder (Al-12Si) and carbon-coated spherical Al-Si pre-alloyed powder (Al-12Si-5C) under low magnification, b and d correspond to the SEM images of spherical Al-Si pre-alloyed powder (Al-12Si) and carbon-coated spherical Al-Si pre-alloyed powder (Al-12Si-5C) under high magnification, respectively; according to Figure 3 It can be seen that by using spherical Al-Si pre-alloyed powder and high-temperature cracking of hydrocarbon compound gas, a layer of carbon can be uniformly coated on the surface of the Al-Si pre-alloyed powder.

[0041] Figure 4 a is the microstructure of spherical Al-Si pre-alloyed powder (Al-12Si), b is the microstructure of spherical SiC / Al-Si composite powder (Al-7Si-5SiC); according to Figure 4 It can be found that after the carburization reaction and the in-situ reaction, fine SiC particles are formed in the spherical Al-Si pre-alloyed powder and still maintain a spherical morphology.

[0042] Example 2

[0043] The present invention provides a method for preparing spherical SiC / Al-Si composite powder, comprising the following steps:

[0044] S1. A spherical Al-Si pre-alloy powder (denoted as Al-40Si, i.e., Al content is 60 wt.%, Si content is 40 wt.%; particle size D) is obtained by gas atomization method (refer to CN110904368A for details). 50 =20 μm);

[0045] S2, 500 g of the spherical Al-Si pre-alloyed powder in S1 was placed in a rotary tube furnace, and acetylene gas (gas flow rate was 600 mL / min) was introduced, and then the rotary tube furnace was heated to 600° C. at a heating rate of 10° C. / min and kept warm for 2 h to obtain a carbon-coated spherical Al-Si pre-alloyed powder (wherein the mass content of carbon was 5 wt.%);

[0046] S3. 500 g of the carbon-coated spherical Al-Si pre-alloyed powder in S2 was heated to 800° C. in an argon atmosphere for 1 h to obtain a spherical SiC / Al-Si composite powder (wherein the mass content of SiC is 5 wt.%).

[0047] Example 3

[0048] The present invention provides a method for preparing spherical SiC / Al-Si composite powder, comprising the following steps:

[0049] S1. A spherical Al-Si pre-alloy powder (denoted as Al-12Si, i.e., Al content is 88 wt.%, Si content is 12 wt.%; particle size D) is obtained by gas atomization method (for details, refer to CN110904368A) 50 =20 μm);

[0050] S2, 500g of the spherical Al-Si pre-alloyed powder in S1 is placed in a gas fluidized bed (such as Figure 1b), and acetylene gas (gas flow rate is 600 mL / min), then the rotary tube furnace is heated to 600° C. at a heating rate of 10° C. / min and kept warm for 2 h to obtain a carbon-coated spherical Al-Si pre-alloyed powder (wherein the mass content of carbon is 5 wt.%);

[0051] S3. 500 g of the carbon-coated spherical Al-Si pre-alloyed powder in S2 was heated to 800° C. in an argon atmosphere for 1 h to obtain a spherical SiC / Al-Si composite powder (wherein the mass content of SiC is 5 wt.%).

[0052] Example 4

[0053] The present invention provides a method for preparing carbon-coated spherical Al-Si pre-alloyed powder, comprising the following steps:

[0054] S1. A spherical Al-Si pre-alloy powder (denoted as Al-12Si, i.e., Al content is 88 wt.%, Si content is 12 wt.%; particle size D) is obtained by gas atomization method (for details, refer to CN110904368A) 50 =20 μm);

[0055] S2, 500 g of the spherical Al-Si pre-alloyed powder in S1 was placed in a rotary tube furnace, and ethylene gas (gas flow rate was 600 mL / min) was introduced, and then the rotary tube furnace was heated to 600° C. at a heating rate of 10° C. / min and kept warm for 2 h to obtain a carbon-coated spherical Al-Si pre-alloyed powder (wherein the mass content of carbon was 5 wt.%);

[0056] S3. 500 g of the carbon-coated spherical Al-Si pre-alloyed powder in S2 was heated to 800° C. in an argon atmosphere for 1 h to obtain a spherical SiC / Al-Si composite powder (wherein the mass content of SiC is 5 wt.%).

[0057] Example 5

[0058] The present invention provides a method for preparing carbon-coated spherical Al-Si pre-alloyed powder, comprising the following steps:

[0059] S1. A spherical Al-Si pre-alloy powder (denoted as Al-12Si, i.e., Al content is 88 wt.%, Si content is 12 wt.%; particle size D) is obtained by gas atomization method (for details, refer to CN110904368A) 50 =20 μm);

[0060] S2, placing 500 g of the spherical Al-Si pre-alloyed powder in S1 into a rotary tube furnace, and introducing acetylene gas (gas flow rate is 600 mL / min), then heating the rotary tube furnace to 550° C. at a heating rate of 10° C. / min for 3 h to obtain a carbon-coated spherical Al-Si pre-alloyed powder (wherein the mass content of carbon is 6 wt.%);

[0061] S3. Heat 500 g of the carbon-coated spherical Al-Si pre-alloyed powder in S2 to 800° C. in an argon atmosphere and keep the temperature for 1 hour to obtain a spherical SiC / Al-Si composite powder (wherein the mass content of SiC is 6 wt.%).

[0062] Performance Testing

[0063] 1) Composite powder fluidity: The powder fluidity was tested using a Hall flow meter. A standard funnel with an aperture of 2.5 mm was used, and 50 g of powder was added. The timing started from when the powder fell from the bottom of the standard funnel until the powder was completely drained. This was repeated three times and the average value was taken.

[0064] 2) Mechanical properties of composite materials: The spherical SiC / Al-Si composite powders prepared in each embodiment were hot extruded by a vertical extruder to obtain SiC / Al-Si composite materials; the specific parameters were extrusion temperature of 450°C, extrusion ratio of 20:1, and extrusion speed of 1 mm / min. Then, a universal testing machine (Instron, 3382, USA) was used to perform a tensile test on the SiC / Al-Si composite material at a tensile rate of 0.5 mm / min. The test standard was based on ASTM, and the tensile test samples were cut along the extrusion direction.

[0065] Table 1 Properties of spherical SiC / Al-Si composite powders and corresponding composite materials in various embodiments

[0066]

[0067]

[0068] According to the data in Table 1, the fluidity of the spherical SiC / Al-Si composite powders in Examples 1 to 5 is ≤32s / 50g, and the tensile strength of the hot-pressed composite material is above 395MPa, indicating that the spherical SiC / Al-Si composite powders prepared by the preparation method of the present invention not only have good fluidity, but also can have a high bonding strength between the Al and SiC interfaces, thereby having excellent mechanical properties.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing spherical SiC / Al-Si composite powder, characterized in that: The following steps are involved: S1, carbonizing the spherical Al-Si pre-alloyed powder and hydrocarbon compound gas at 400-700° C. for 1-10 hours to obtain carbon-coated spherical Al-Si pre-alloyed powder; S2, reacting the carbon-coated spherical Al-Si pre-alloyed powder in S1 in situ at 750-1000° C. in an inert gas atmosphere for 0.5-10 h to obtain a spherical SiC / Al-Si composite powder; The hydrocarbon compound gas in S1 includes at least one of alkane gas, olefin gas and alkyne gas.

2. The preparation method according to claim 1, characterized in that The mass volume ratio of the spherical Al-Si pre-alloyed powder to the hydrocarbon compound gas is g / mL=(100-1000):(100-500).

3. The preparation method according to claim 1, characterized in that: The particle size D of the spherical Al-Si pre-alloyed powder 50 ≤60μm.

4. The preparation method according to claim 1, characterized in that: The spherical Al-Si pre-alloyed powder is mainly composed of Al and Si, wherein the mass content of Si is 5wt.% to 60wt.%.

5. The preparation method according to claim 1, characterized in that: The mass content of carbon in the carbon-coated spherical Al-Si pre-alloyed powder in S1 is 1 wt.% to 30 wt.%.

6. The preparation method according to claim 1, characterized in that: The mass content of SiC in the spherical SiC / Al-Si composite powder in S2 is 1 wt.% to 30 wt.%.

7. The preparation method according to claim 1, characterized in that: The alkane gas is at least one of methane, ethane and propane; And / or, the olefin gas is at least one of ethylene, propylene and butene; And / or, the alkyne gas is at least one of acetylene and propyne.

8. The preparation method according to claim 1, characterized in that: Step S1 specifically includes placing the spherical Al-Si pre-alloyed powder in an atmosphere rotary tube furnace or a gas fluidized bed, introducing hydrocarbon compound gas, and carbonizing at 400-700° C. for 1-10 hours to obtain carbon-coated spherical Al-Si pre-alloyed powder.

9. Spherical SiC / Al-Si composite powder obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the spherical SiC / Al-Si composite powder according to claim 9 in preparing a radio frequency receiver packaging shell, a radar circuit shell or an engine piston.

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