Aluminum nitride-coated aluminum-strontium alloy, and preparation method and application thereof

Abstract

The application belongs to the technical field of metal materials and its preparation, and discloses an aluminum nitride coated aluminum strontium alloy and a preparation method and application thereof. The preparation method is as follows: an aluminum strontium alloy ingot is sheared and then hot extruded to form a desired shape to obtain an aluminum strontium alloy crude product; then, an AlN powder is sprayed on the surface of the aluminum strontium alloy crude product by using a plasma spraying technology to form an AlN coating, thereby obtaining the aluminum nitride coated aluminum strontium alloy; wherein the strontium content in the aluminum strontium alloy ingot is 50wt%-90wt%; and the thickness of the AlN coating is 50-400 µm. The aluminum nitride coated aluminum strontium alloy prepared by the application can not only improve the efficiency of strontium modification of aluminum-silicon alloy, but also prevent the strontium element in the aluminum strontium alloy from being oxidized, and meanwhile, the AlN coating can form a dispersed nano-strengthening phase AlN in the aluminum-silicon alloy matrix, thereby further improving the mechanical properties of the aluminum-silicon alloy.

Description

Technical Field

[0001] This invention relates to the field of metallic materials and their preparation technology, and in particular to an aluminum nitride-coated aluminum strontium alloy, its preparation method, and its application. Background Technology

[0002] Aluminum-strontium modification is commonly used for the modification of hypoeutectic and eutectic aluminum-silicon alloys. Common aluminum-strontium master alloys mainly use Al-5Sr and Al-10Sr modifiers, added at approximately 2wt%–6wt% of the aluminum-silicon alloy. This modifier modifies needle-like or plate-like eutectic silicon and coarse primary silicon, changing the silicon morphology from needle-like or plate-like to uniform spherical, further improving the mechanical properties of the aluminum-silicon alloy. Aluminum-strontium modification offers advantages such as easy control of strontium content, simple operation, and no incomplete or over-modification during the process; strontium has a long-lasting effect on the modification of aluminum-silicon alloys; the microstructure of the modified alloy does not change significantly after remelting, and it is non-toxic and non-polluting.

[0003] Traditional aluminum-strontium master alloys have low strontium content, requiring a long modification time. Furthermore, strontium is chemically reactive and easily oxidized, leading to the use of large quantities. This makes the aluminum-silicon alloy prone to hydrogen absorption, resulting in porosity defects after alloy forming. Simultaneously, it consumes a large amount of strontium, increasing the cost of the final alloy casting. To avoid these issues, existing technologies mainly employ increasing the number of degassing and refining cycles. However, this method is time-consuming, energy-intensive, and material-intensive, hindering its widespread adoption for large-scale production.

[0004] Therefore, the present invention provides an aluminum nitride-coated aluminum strontium alloy, its preparation method and application. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides an aluminum nitride-coated aluminum-strontium alloy, its preparation method, and its applications. This invention provides an aluminum-strontium master alloy with a strontium content of 50% or higher, up to a maximum of 90%, improving the efficiency of strontium in modifying aluminum-silicon alloys. When the strontium content in the aluminum-strontium master alloy exceeds 10%, the strontium in the alloy is easily oxidized, making it difficult to store and use. Currently, oxidation is mainly prevented by sealing it in aluminum tubes. However, this invention, during the master alloy forming process, involves plasma-spraying a 50-400 μm aluminum nitride (AlN) coating onto its surface. This not only prevents the oxidation of strontium in the aluminum-strontium alloy but also allows the AlN coating to form a dispersed nano-reinforcing AlN phase within the aluminum-silicon alloy matrix, further improving the mechanical properties of the aluminum-silicon alloy.

[0006] The present invention relates to an aluminum nitride-coated aluminum-strontium alloy, its preparation method, and its application, which are achieved through the following technical solutions: The first objective of this invention is to provide a method for preparing aluminum nitride-coated aluminum-strontium alloy, comprising the following steps: The aluminum-strontium alloy ingot is sheared and then hot-extruded to form the required shape to obtain a crude aluminum-strontium alloy product. Subsequently, AlN powder is sprayed onto the surface of the crude aluminum-strontium alloy product using plasma spraying technology to form an AlN coating, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy. The strontium content in the aluminum-strontium alloy ingot is 50wt%~90wt%; The thickness of the AlN coating is 50~400µm.

[0007] Preferably, the working gas of the plasma spraying technology is hydrogen and argon; The hydrogen pressure is 0.5~0.9MPa, and the hydrogen flow rate is 25~35L / min; The argon pressure is 0.2~0.4MPa, and the argon flow rate is 8~15 L / min; Operating current is 550~650A; operating voltage is 65~85V; The spraying distance is 70~100mm; Furthermore, the speed at which the robotic arm drives the spray gun is 300~500mm / s.

[0008] Preferably, the aluminum-strontium alloy ingot is obtained through the following steps: Pure aluminum ingots are added to a medium-frequency induction furnace and melted until completely melted. Then, they are refined and degassed at 710~740℃. After standing for 10~15 minutes, the slag is removed to obtain pure aluminum melt. The aluminum melt is heated to 780~950℃, weighed strontium metal is added, and after sealing, a vacuum is drawn at a temperature of 780~950℃. The melt is then subjected to heat preservation treatment in the vacuum to obtain an aluminum-strontium alloy melt. The obtained aluminum-strontium alloy melt is subjected to electromagnetic stirring in a vacuum, and after slag removal, it is cast to obtain aluminum-strontium alloy ingots. The purity of the pure aluminum ingot is ≥99.7%; Furthermore, the ambient humidity is kept ≤45% during the preparation of aluminum-strontium alloy ingots.

[0009] Preferably, the process parameters for the refining and degassing are: Argon gas pressure: 0.1~0.3 MPa; The rotor speed is 800~1500 r / min, and the degassing time is 10~30 min.

[0010] Preferably, the heat preservation treatment time is 45~90 minutes; The casting temperature is 850~1300℃.

[0011] Preferably, the power of the electromagnetic stirrer is 150~200kW, and the electromagnetic stirring time is 2~5min.

[0012] Preferably, the particle size of the AlN powder is 0.2~2μm.

[0013] The second objective of this invention is to provide an aluminum nitride-coated aluminum strontium alloy prepared by the above-described preparation method.

[0014] A third objective of this invention is to apply the above-mentioned aluminum nitride-coated aluminum strontium alloy to modified and particle-strengthened aluminum-silicon alloys, using the above-prepared aluminum nitride-coated aluminum strontium alloy as a modifier.

[0015] Preferably, the aluminum nitride-coated aluminum-strontium alloy is modified and particle-strengthened aluminum-silicon alloy through the following steps: After the aluminum-silicon alloy is completely melted, it is degassed and slag removed to obtain the aluminum-silicon alloy melt. When the aluminum-silicon alloy melt is at 650~750℃, the aluminum nitride-coated aluminum-strontium alloy is added, and the mixture is allowed to stand for 10~15 minutes to completely melt the aluminum nitride-coated aluminum-strontium alloy, thus obtaining a mixed melt. The mixed melt is incubated at 710~730℃ for 10~15min to achieve the modification treatment of aluminum-silicon alloy; The mass ratio of the aluminum nitride-coated aluminum strontium alloy to the aluminum silicon alloy is 0.03wt%~0.05wt%:1.

[0016] Compared with the prior art, the present invention has the following advantages: This invention provides an aluminum-strontium master alloy with a strontium content of 50% or higher, up to 90%, thereby improving the efficiency of strontium in modifying aluminum-silicon alloys. When the strontium content in the aluminum-strontium master alloy exceeds 10%, the strontium in the alloy is easily oxidized, making it difficult to store and use. Currently, oxidation is mainly prevented by sealing it in an aluminum tube. However, this invention involves plasma spraying a 50-400 μm aluminum nitride (AlN) coating onto the surface of the master alloy during the forming process. This not only prevents the oxidation of strontium in the aluminum-strontium alloy but also allows the AlN coating to form a dispersed nano-reinforcing phase AlN in the aluminum-silicon alloy matrix, further improving the mechanical properties of the aluminum-silicon alloy.

[0017] The low melting point (580°C) of aluminum-strontium alloys with a strontium content of over 50% allows for the processing of aluminum-silicon alloy melts at lower metal temperatures. This reduces the absorption of oxides and [H] gas in the aluminum-silicon alloy, decreases burn-off and energy consumption, and thus reduces the total casting cost.

[0018] The 50-400μm aluminum nitride (AlN) coating thermally sprayed onto the surface of aluminum-strontium alloys in this invention can prevent the oxidation of strontium and can also form a dispersed nanoparticle reinforcing phase in the aluminum-silicon alloy matrix, which can greatly improve its mechanical properties. Attached Figure Description

[0019] Figure 1 The image shows the metallographic structure of the hypoeutectic aluminum-silicon alloy after modification treatment in Comparative Example 1. Figure 2 This is a metallographic distribution diagram of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 4; Figure 3 The image shows the metallographic structure of the hypoeutectic aluminum-silicon alloy after modification treatment in Comparative Example 2. Figure 4 This is a metallographic distribution diagram of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 5; Figure 5 This is a distribution diagram of the dispersed AlN nano-reinforcing phase formed in the matrix of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 4. Figure 6 This is a distribution diagram of the dispersed AlN nano-reinforcing phase formed in the matrix of the hypoeutectic aluminum-silicon alloy after the modification treatment in Example 5. Figure 7 The silicon phase morphology after deep corrosion testing of the hypoeutectic aluminum-silicon alloy modified in Comparative Example 1. Figure 8 The silicon phase morphology after deep corrosion testing of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 4. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0021] This invention provides an aluminum nitride-coated aluminum-strontium alloy, and its preparation method is as follows: The aluminum-strontium alloy ingot is sheared and then hot-extruded to form the required shape to obtain a crude aluminum-strontium alloy product. Subsequently, AlN powder is sprayed onto the surface of the crude aluminum-strontium alloy product using plasma spraying technology to form an AlN coating, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy. The strontium content in the aluminum-strontium alloy ingot is 50wt%~90wt%; The thickness of the AlN coating is 50~400µm.

[0022] It should be noted that, in order to improve the efficiency of strontium modification of aluminum-silicon alloys, in a preferred embodiment of this invention, an aluminum-strontium alloy ingot with a strontium content of 50wt%~90wt% is used as the matrix to improve the efficiency of strontium modification of aluminum-silicon alloys. Furthermore, this invention considers that when aluminum-strontium alloy ingots are used to modify aluminum-silicon alloys, if the strontium content in the aluminum-strontium intermediate alloy exceeds 10%, the strontium element in the alloy is easily oxidized, making it difficult to store and use. To avoid oxidation of the aluminum-strontium alloy ingot with a strontium content of 50wt%~90wt% used in this invention during practical application, this invention uses plasma spraying technology to spray an AlN coating on its surface. The formation of the AlN coating on its surface not only prevents the oxidation of the strontium element in the aluminum-strontium alloy, but also allows the AlN coating to form a dispersed nano-reinforcing phase AlN in the aluminum-silicon alloy matrix, further improving the mechanical properties of the aluminum-silicon alloy. Furthermore, in order to improve the mechanical properties of aluminum-silicon alloys while ensuring that aluminum-strontium alloy ingots with a strontium content of 50wt%~90wt% do not oxidize in practical applications, in a preferred embodiment of the present invention, the thickness of the formed AlN coating is 50~400µm.

[0023] To ensure the formation of an AlN coating with a thickness of 50-400µm, in a preferred embodiment of this invention, the AlN powder used has a particle size of 0.2-2µm. The plasma spraying parameters are as follows: working gases are hydrogen and argon; hydrogen pressure is 0.5-0.9MPa, and hydrogen flow rate is 25-35L / min; argon pressure is 0.2-0.4MPa, and argon flow rate is 8-15 L / min; working current is 550-650A; working voltage is 65-85V; spraying distance is 70-100mm; and the speed at which the robotic arm moves the spray gun is 300-500mm / s. Argon is the primary gas, and hydrogen is an auxiliary gas used to generate the plasma flame and increase its temperature.

[0024] Furthermore, to ensure the acquisition of aluminum-strontium alloy ingots with a strontium content of 50wt%~90wt%, the present invention is prepared by the following method: Pure aluminum ingots are added to a medium-frequency induction furnace for smelting to obtain molten liquid; When the temperature of the molten liquid is 710~740℃, it is refined and degassed, and after standing for 10~15 minutes, the slag is removed to obtain pure aluminum melt. The aluminum melt is heated to 780~950℃, weighed strontium metal is added, and after sealing, a vacuum is drawn at a temperature of 780~950℃. The melt is then subjected to heat preservation treatment, electromagnetic stirring treatment, and slag removal treatment in the vacuum before casting to obtain aluminum-strontium alloy ingots.

[0025] To ensure the availability of aluminum-strontium alloy ingots with a strontium content of 50wt%~90wt%, the mass ratio of pure aluminum ingots to metallic strontium used in this invention is 10~50:50~90.

[0026] It should be noted that, to avoid excessive porosity in the obtained aluminum-strontium alloy, the ambient humidity must be maintained at ≤45% during the preparation of the aluminum-strontium alloy in this invention. This prevents the aluminum melt or aluminum-strontium alloy melt from reacting with moisture in the environment to generate [H], 2Al(l) + 3H2O(g) → Al2O3(s) + 6[H]; otherwise, the melt will contain a large amount of [H], leading to the formation of pores during solidification. Considering that the equipment is too large for dehumidification, this invention allows for preparation to be carried out in sunny and dry weather.

[0027] To avoid introducing other impurities, in a preferred embodiment of the present invention, the purity of the pure aluminum ingot used is ≥99.7%.

[0028] To ensure the purity of the molten aluminum, this invention first adds pure aluminum ingots to a medium-frequency induction furnace and melts them until completely molten. Therefore, this invention does not limit the melting temperature and time, as long as the pure aluminum ingots can be completely melted into a molten liquid, such as at 710~740℃. Furthermore, considering the potential presence of [H] and slag in the molten liquid obtained from the melting process, this invention refines and degasses the molten liquid at a temperature of 710~740℃ to effectively remove [H] and slag from the molten aluminum.

[0029] To ensure effective removal of [H] and slag from molten aluminum, in a preferred embodiment of the present invention, refining and degassing is carried out using a combination of argon rotary blowing and vacuum methods. The specific refining and degassing process parameters are as follows: in an environment with a vacuum degree of -0.06 ~ -0.1MPa, argon gas pressure is 0.1 ~ 0.3MPa; the rotor speed is 800 ~ 1500 r / min; and the degassing time is 10 ~ 30 min, to ensure effective removal of [H] and slag from molten aluminum and obtain pure aluminum melt.

[0030] Considering that [H] and slag need a certain amount of time to float, in a preferred embodiment of the present invention, after degassing, the mixture is first allowed to stand for 10 to 15 minutes to ensure that [H] and slag float fully. Then, the slag removal process is used to clean the oxides, inclusions and other harmful substances in the molten aluminum, thereby obtaining a pure molten aluminum.

[0031] In order to ensure that strontium and aluminum can be fully mixed, the aluminum melt is first heated to 780~950°C, and then metallic strontium is added to ensure that metallic strontium can be fully melted in the aluminum melt at this temperature.

[0032] After adding metallic strontium, the present invention first evacuates the vacuum to -0.06 ~ -0.1 MPa at a temperature of 780~950℃, and then holds the temperature for 45~90 minutes to prevent strontium from absorbing [H] and oxidizing in the aluminum melt.

[0033] To further ensure that strontium and aluminum can be fully mixed, the present invention further applies electromagnetic stirring to the heat-insulated aluminum-strontium alloy melt, with the electromagnetic stirring power being 150~200kW and the electromagnetic stirring time being 2~5min.

[0034] The present invention involves opening the furnace cover for slag removal during electromagnetic stirring, then pouring the molten aluminum-strontium alloy into a continuous casting machine at 850~1300℃, and then cutting the continuously cast aluminum-strontium alloy trapezoidal ingot into multiple square wires in a shearing machine according to actual needs. Finally, aluminum-strontium alloy rods of the required size are obtained through a continuous hot extrusion mechanism. The above process is a continuous process.

[0035] This invention also provides a method for modifying aluminum-silicon alloys using the aluminum nitride-coated aluminum-strontium alloy prepared according to this invention, comprising the following steps: After the aluminum-silicon alloy is completely melted, it is degassed and slag-removed. The aluminum nitride-coated aluminum-strontium alloy prepared in this invention is added at a temperature of 690~760℃. After the aluminum nitride-coated aluminum-strontium alloy is completely melted, it is inoculated at 710~730℃ for 10~15 minutes, which achieves the modification treatment of aluminum-silicon alloy. The aluminum-silicon alloy is either Al-7Si or Al-12Si.

[0036] Example 1 This embodiment provides an aluminum nitride-coated aluminum-strontium alloy, and its preparation method is as follows: Step 1, Prepare aluminum-strontium alloy ingots: 1) Weigh 10 kg of pure aluminum ingots with a purity ≥ 99.7% and add them to a medium-frequency induction furnace. Melt them at 730℃ until they are completely melted. At this temperature, argon gas is introduced at a pressure of 0.2 MPa, the rotor speed is 1100 r / min, and the degassing time is 20 min for refining and degassing. After standing for 12 min, the slag is removed to obtain pure aluminum melt. 2) Heat the above aluminum melt to 900℃, add 90kg of metallic strontium, seal the furnace chamber with a sealed furnace lid, and then evacuate at 900℃ until the vacuum degree inside the furnace is -0.08MPa. Continue to hold at 900℃ in the vacuum for 70 minutes to obtain aluminum-strontium alloy melt. 3) Adjust the power of the medium frequency furnace to 170kW to electromagnetically stir the aluminum-strontium alloy melt obtained above in a vacuum for 3 minutes, so that the Al4Sr particles in the alloy are evenly dispersed. 4) Open the furnace cover to remove slag, and then pour the aluminum-strontium alloy melt after slag removal into the continuous casting machine at a temperature of 1000℃ to obtain aluminum-strontium alloy ingots.

[0037] Step 2: Coating the aluminum-strontium alloy surface with AlN: 1) The aluminum-strontium alloy ingots continuously cast in step 1 are cut into multiple square wires in a shearing machine, and finally aluminum-strontium alloy rods with a diameter of φ10mm are obtained through a continuous hot extrusion mechanism. The above process is a continuous process. 2) Plasma spraying technology is adopted, and the working parameters of plasma spraying are set as follows: working gases are hydrogen and argon; hydrogen pressure is 0.6MPa, hydrogen flow rate is 30L / min; argon pressure is 0.3MPa, argon flow rate is 11 L / min; working current is 600A; working voltage is 75V; spraying distance is 85mm; the speed at which the robotic arm moves the spray gun is 400mm / s. Using AlN powder with a particle size of 1μm as the spraying powder, it is plasma sprayed onto the surface of the aluminum-strontium alloy rod according to the above plasma spraying working parameters to form an AlN coating with a thickness of 200µm, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy.

[0038] In this embodiment, the aluminum nitride-coated aluminum strontium alloy has a strontium content of 90 wt%, and is named AlN-coated Al-90Sr.

[0039] Example 2 This embodiment provides an aluminum nitride-coated aluminum-strontium alloy, and its preparation method is as follows: Step 1, Prepare aluminum-strontium alloy ingots: 1) Weigh 50 kg of pure aluminum ingots with a purity ≥ 99.7% and add them to a medium-frequency induction furnace. Melt them at 710℃ until they are completely melted. At this temperature, argon gas is introduced at a pressure of 0.1 MPa, the rotor speed is 800 r / min, and the degassing time is 10 min for refining and degassing. After standing for 10 min, the slag is removed to obtain pure aluminum melt. 2) Heat the above aluminum melt to 780°C, add 50 kg of metallic strontium, seal the furnace chamber with a sealed furnace lid, and then evacuate at 780°C until the vacuum degree inside the furnace is -0.06 MPa. Continue to hold at 780°C in the vacuum for 45 min to obtain aluminum-strontium alloy melt. 3) Adjust the power of the medium frequency furnace to 150kW to electromagnetically stir the aluminum-strontium alloy melt obtained above in a vacuum for 2 minutes, so that the Al4Sr particles in the alloy are evenly dispersed. 4) Open the furnace cover to remove slag, and then pour the aluminum-strontium alloy melt after slag removal into the continuous casting machine at a temperature of 850°C to obtain aluminum-strontium alloy ingots by continuous casting.

[0040] Step 2: Coating the aluminum-strontium alloy surface with AlN: 1) The aluminum-strontium alloy ingots continuously cast in step 1 are cut into multiple square wires in a shearing machine, and finally aluminum-strontium alloy rods with a diameter of φ10mm are obtained through a continuous hot extrusion mechanism. The above process is a continuous process. 2) Plasma spraying technology is adopted, and the working parameters of plasma spraying are set as follows: working gases are hydrogen and argon; hydrogen pressure is 0.5MPa, hydrogen flow rate is 25L / min; argon pressure is 0.2MPa, argon flow rate is 8 L / min; working current is 550A; working voltage is 65V; spraying distance is 70mm; the speed at which the robotic arm moves the spray gun is 300mm / s. Using AlN powder with a particle size of 2μm as the spraying powder, it is plasma sprayed onto the surface of the aluminum-strontium alloy rod according to the above plasma spraying working parameters to form an AlN coating with a thickness of 50µm, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy.

[0041] In this embodiment, the aluminum nitride-coated aluminum strontium alloy has a strontium content of 50 wt%, and is named AlN-coated Al-50Sr.

[0042] Example 3 This embodiment provides an aluminum nitride-coated aluminum-strontium alloy, and its preparation method is as follows: Step 1, Prepare aluminum-strontium alloy ingots: 1) Weigh 30 kg of pure aluminum ingots with a purity ≥ 99.7% and add them to a medium-frequency induction furnace. Melt them at 740℃ until they are completely melted. At this temperature, argon gas is introduced at a pressure of 0.3 MPa, the rotor speed is 1500 r / min, and the degassing time is 30 min for refining and degassing. After standing for 15 min, the slag is removed to obtain pure aluminum melt. 2) Heat the above aluminum melt to 950°C, add 70 kg of metallic strontium, seal the furnace chamber with a sealed furnace lid, and then evacuate the furnace at 950°C until the vacuum degree inside the furnace is -0.1 MPa. Continue to hold the furnace at 950°C for 90 min in the vacuum to obtain aluminum-strontium alloy melt. 3) Adjust the power of the medium frequency furnace to 200kW to electromagnetically stir the aluminum-strontium alloy melt obtained above in a vacuum for 5 minutes, so that the Al4Sr particles in the alloy are evenly dispersed. 4) Open the furnace cover to remove slag, and then pour the aluminum-strontium alloy melt after slag removal into the continuous casting machine at a temperature of 1300℃ to obtain aluminum-strontium alloy ingots by continuous casting.

[0043] Step 2: Coating the aluminum-strontium alloy surface with AlN: 1) The aluminum-strontium alloy ingots continuously cast in step 1 are cut into multiple square wires in a shearing machine, and finally aluminum-strontium alloy rods with a diameter of φ10mm are obtained through a continuous hot extrusion mechanism. The above process is a continuous process. 2) Plasma spraying technology is adopted, and the working parameters of plasma spraying are set as follows: working gases are hydrogen and argon; hydrogen pressure is 0.9MPa, hydrogen flow rate is 35L / min; argon pressure is 0.4MPa, argon flow rate is 15 L / min; working current is 650A; working voltage is 85V; spraying distance is 100mm; the speed at which the robotic arm moves the spray gun is 200mm / s. Using AlN powder with a particle size of 0.2 μm as the spraying powder, it is plasma sprayed onto the surface of the aluminum-strontium alloy rod according to the above plasma spraying working parameters to form an AlN coating with a thickness of 400 µm, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy.

[0044] In this embodiment, the aluminum nitride-coated aluminum strontium alloy has a strontium content of 70 wt%, and is named AlN-coated Al-70Sr.

[0045] Example 4 This embodiment provides an application of aluminum nitride-coated aluminum-strontium alloy in the modification and particle-strengthened aluminum-silicon alloy. Specifically, this embodiment uses AlN-coated Al-90Sr prepared in Example 1 as a modifier, and performs modification treatment on Al-7Si aluminum-silicon alloy using the following steps: 1) In this embodiment, an Al-7Si aluminum-silicon alloy with a silicon content of 7wt% Si and the remainder being Al is used as the target for strengthening; and according to the mass ratio of aluminum nitride-coated aluminum-strontium alloy to Al-7Si aluminum-silicon alloy of 0.04wt%:1, the corresponding masses of aluminum nitride-coated aluminum-strontium alloy and Al-7Si aluminum-silicon alloy are weighed and mixed for later use. 2) After the weighed Al-7Si aluminum-silicon alloy is melted at 720℃ (the temperature can fluctuate by 10℃) until it is completely melted, 1% by mass of hexachloroethane of Al-7Si aluminum-silicon alloy is added to degas and remove slag to obtain aluminum-silicon alloy melt. 3) The mixed melt is incubated at 720°C for 10-15 minutes to achieve the modification treatment of aluminum-silicon alloy and obtain modified and particle-strengthened aluminum-silicon alloy, namely hypoeutectic aluminum-silicon alloy.

[0046] Example 5 This embodiment provides an application of aluminum nitride-coated aluminum-strontium alloy in the modification and particle-strengthened aluminum-silicon alloy. Specifically, this embodiment uses AlN-coated Al-90Sr prepared in Example 1 as a modifier, and performs the following steps to modify the Al-12Si aluminum-silicon alloy: 1) In this embodiment, an Al-12Si aluminum-silicon alloy with a silicon content of 12wt% Si and the remainder being Al is used as the target for strengthening; and according to the mass ratio of aluminum nitride-coated aluminum-strontium alloy to Al-12Si aluminum-silicon alloy of 0.04wt%:1, the corresponding masses of aluminum nitride-coated aluminum-strontium alloy and Al-12Si aluminum-silicon alloy are weighed and mixed for later use; 2) After the weighed Al-12Si aluminum-silicon alloy is melted at 720℃ (the temperature can fluctuate by 10℃) until it is completely melted, 1% of the mass of Al-12Si aluminum-silicon alloy in hexachloroethane is added to degas and remove slag, and the aluminum-silicon alloy melt is obtained. 3) The mixed melt is incubated at 720°C for 10-15 minutes to achieve the modification treatment of aluminum-silicon alloy and obtain modified and particle-strengthened aluminum-silicon alloy, namely hypoeutectic aluminum-silicon alloy.

[0047] Comparative Example 1 The only difference between this comparative example and Example 4 is that: The modifier in this comparative example is an Al-10Sr alloy (Sr content is 10wt%, balance is Al).

[0048] Comparative Example 2 The only difference between this comparative example and Example 5 is that: The modifier in this comparative example is an Al-10Sr alloy (Sr content is 10wt%, balance is Al).

[0049] Experimental Section 1) Metallographic structure analysis The present invention tested the metallographic structure of hypoeutectic aluminum-silicon alloys after modification treatment in Comparative Example 1 and Example 4, and the test results are as follows: Figure 1 and Figure 2 As shown.

[0050] And by Figure 1 and Figure 2 It can be seen that the eutectic Si phase is refined and the spacing between secondary dendrite arms is smaller and more obvious, and a large number of dispersed AlN nanoparticles are formed in the matrix to reinforce the phase.

[0051] The present invention tested the metallographic structure of the hypoeutectic aluminum-silicon alloys after modification treatment in Comparative Example 2 and Example 5, respectively, and the test results are as follows: Figure 3 and Figure 4 As shown.

[0052] And by Figure 3 and Figure 4 It can be seen that the hypereutectic and eutectic Si phases are more refined and granulated, and a large number of dispersed AlN nanoparticles are formed in the matrix to reinforce the phase.

[0053] 2) Analysis of dispersed AlN nano-reinforced phase In Example 4 of this invention, the dispersed AlN nano-reinforcing phase formed in the matrix of the hypoeutectic aluminum-silicon alloy after modification treatment is as follows: Figure 5 As shown, it can be seen that there are obvious nanoscale dispersed AlN particles in the matrix of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 4. The nanoscale dispersed AlN particles can strengthen the alloy and thus improve the strength of the alloy material.

[0054] The present invention also addresses the dispersed AlN nano-reinforcing phase formed in the matrix of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 5. Figure 6 As shown in the figure, the black granular nanophase is clearly the dispersed AlN nano-reinforcing phase formed in the matrix. This indicates that by plasma-spraying an AlN coating onto the surface of the intermediate alloy during the forming process, the present invention can indeed enable the AlN coating to form a dispersed AlN nano-reinforcing phase in the aluminum-silicon alloy matrix, thereby further improving the mechanical properties of the aluminum-silicon alloy.

[0055] 3) Analysis of silicon phase morphology after deep etching This invention also conducted deep corrosion tests on the hypoeutectic aluminum-silicon alloys after modification treatment in Comparative Example 1 and Example 4, and tested the silicon phase morphology after deep corrosion. The test results are as follows: Figure 7 and Figure 8 As shown.

[0056] in, Figure 7 The silicon phase morphology after deep corrosion testing of the hypoeutectic aluminum-silicon alloy modified in Comparative Example 1. Figure 8 The silicon phase morphology after deep corrosion testing of the hypoeutectic aluminum-silicon alloy after modification treatment in Example 4 is shown. Furthermore, a comparison was made... Figure 7 and Figure 8 It can be seen that different modifiers have significantly different effects on the modification of the silicon phase, and Figure 8 The silicon phase in it is significantly larger than Figure 7 The fine silicon phase indicates that the modifier used in Example 4 of this invention is more efficient than the modifier in the prior art.

[0057] 4) Actual yield test This invention uses ICP plasma spectroscopy to test the actual yield of modifiers in hypoeutectic aluminum-silicon alloys after modification treatment in Example 4 and Comparative Example 1, respectively. The tests show that the actual yield of Al-10 Strontium modification can reach about 94%, and the actual yield of Al-90 Strontium modification after AlN coating Al-90Sr modification can reach more than 98%. This indicates that after treatment by this invention, the microstructure is more refined, and the heterogeneous core particles Al4Sr play an excellent modification effect, thereby improving the absorption rate.

[0058] The present invention tested the actual yield of modifiers in hypoeutectic aluminum-silicon alloys after modification treatment in Example 5 and Comparative Example 2, respectively. It can be seen that the actual yield of Al-10 strontium modification can reach about 94%, and the actual yield of Al-90 strontium modification with AlN coating Al-90Sr can reach more than 98%.

[0059] 5) Mechanical property testing According to the test methods in GB / T 228.1-2021 Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method, the mechanical properties of the hypoeutectic aluminum-silicon alloys after modification treatment in Example 4 and Comparative Example 1 were tested. According to the test results, the strength of the aluminum-silicon alloy after Al-10Sr modification is about 201 MPa, and the strength of the aluminum-silicon alloy after AlN-coated Al-90Sr modification is about 244 MPa, with the strength increasing by about 21.4%.

[0060] According to the test methods in GB / T 228.1-2021 Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method, the mechanical properties of the hypoeutectic aluminum-silicon alloys after modification treatment in Example 5 and Comparative Example 2 were tested. It was found that the strength of the aluminum-silicon alloy after Al-10Sr modification was about 186 MPa, and the strength of the aluminum-silicon alloy after AlN-coated Al-90Sr modification was about 227 MPa, with the strength increasing by about 22.0%.

[0061] Obviously, the above embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum nitride-coated aluminum-strontium alloy, characterized in that, Includes the following steps: The aluminum-strontium alloy ingot is sheared and then hot-extruded to form the required shape to obtain a crude aluminum-strontium alloy product. Subsequently, AlN powder is sprayed onto the surface of the crude aluminum-strontium alloy product using plasma spraying technology to form an AlN coating, thereby obtaining the aluminum nitride-coated aluminum-strontium alloy. The strontium content in the aluminum-strontium alloy ingot is 50wt%~90wt%; The thickness of the AlN coating is 50~400µm; The working gases for the plasma spraying technology are hydrogen and argon. The hydrogen pressure is 0.5~0.9MPa, and the hydrogen flow rate is 25~35L / min; The argon pressure is 0.2~0.4MPa, and the argon flow rate is 8~15 L / min; Operating current is 550~650A; operating voltage is 65~85V; The spraying distance is 70~100mm; The robotic arm drives the spray gun at a speed of 300~500mm / s.

2. The preparation method according to claim 1, characterized in that, The aluminum-strontium alloy ingot is obtained through the following steps: Pure aluminum ingots are added to a medium-frequency induction furnace and melted until completely melted. Then, they are refined and degassed at 710~740℃. After standing for 10~15 minutes, the slag is removed to obtain pure aluminum melt. The aluminum melt is heated to 780~950℃, weighed strontium metal is added, the mixture is sealed, and a vacuum is drawn at 780~950℃. The mixture is then kept warm in the vacuum to obtain an aluminum-strontium alloy melt. The aluminum-strontium alloy melt was subjected to electromagnetic stirring in a vacuum, and after slag removal, it was cast to obtain aluminum-strontium alloy ingots. The purity of the pure aluminum ingot is ≥99.7%; Furthermore, the ambient humidity is kept ≤45% during the preparation of aluminum-strontium alloy ingots.

3. The preparation method according to claim 2, characterized in that, The refining and degassing process parameters are as follows: The argon gas pressure is 0.1~0.3MPa; The rotor speed is 800~1500 r / min, and the degassing time is 10~30 min.

4. The preparation method according to claim 2, characterized in that, The heat preservation treatment time is 45~90 minutes; The casting temperature is 850~1300℃.

5. The preparation method according to claim 2, characterized in that, The electromagnetic stirring power is 150~200kW, and the electromagnetic stirring time is 2~5min.

6. The preparation method according to claim 1, characterized in that, The particle size of the AlN powder is 0.2~2μm.

7. An aluminum nitride-coated aluminum strontium alloy prepared by the preparation method according to any one of claims 1-6.

8. The application of the aluminum nitride-coated aluminum strontium alloy of claim 7 in modified and particulate-strengthened aluminum-silicon alloys, characterized in that, The aluminum nitride-coated aluminum strontium alloy prepared according to claim 7 is used as a modifier.

9. The application as described in claim 8, characterized in that, The aluminum nitride-coated aluminum-strontium alloy is modified and particle-strengthened aluminum-silicon alloy through the following steps: After the aluminum-silicon alloy is completely melted, it is degassed and slag removed to obtain the aluminum-silicon alloy melt. When the aluminum-silicon alloy melt is at 650~750℃, the aluminum nitride-coated aluminum-strontium alloy is added, and the mixture is allowed to stand for 10~15 minutes to completely melt the aluminum nitride-coated aluminum-strontium alloy, thus obtaining a mixed melt. The mixed melt is incubated at 710~730℃ for 10~15 minutes to achieve the modification treatment of aluminum-silicon alloy; The mass ratio of the aluminum nitride-coated aluminum strontium alloy to the aluminum silicon alloy is 0.03wt%~0.05wt%:1.

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