Preparation method of magnesium-aluminum alloy with high strength and corrosion resistance

Abstract

The invention discloses a preparation method of a magnesium-aluminum alloy with high strength and corrosion resistance, and relates to the technical field of magnesium-aluminum alloys, and the preparation method comprises the following steps: heating an aluminum ingot to 800 DEG C according to a fixed proportion by weight, adding zirconium powder and scandium powder, and then stirring; adding niobium powder and titanium powder, continuously stirring for 30 minutes to form an intermediate alloy melt, pouring the melt into a rotating copper roller, stirring for 30 minutes at the rotating speed of 3000rpm for solidification, adding calcium particles and strontium particles, and continuously stirring for 20 minutes at the rotating speed of 3000rpm; adding a part # imgabs0 # agent, refining for 2 hours, then standing for 10 minutes, and skimming surface scum to obtain a magnesium-aluminum alloy melt; by adding trace elements, the strength and corrosion resistance of the magnesium-aluminum alloy are remarkably improved; through vacuum heating and refining treatment, gas and impurities are effectively removed, defects are reduced, the alloy density and melt purity are improved, in the melt treatment stage, solid-liquid two-phase coexisting semi-solid slurry is formed by controlling the temperature and stirring, the fluidity and formability are further improved, and casting defects are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium-aluminum alloys, and more specifically, to a preparation method of a magnesium-aluminum alloy with high strength and corrosion resistance. Background Art

[0002] Due to its low density, high strength, good corrosion resistance and other characteristics, magnesium-aluminum alloy is widely used in many fields and has broad application prospects in the fields of aerospace, automobile manufacturing, electronic equipment, etc. However, the magnesium-aluminum matrix is prone to react with water, oxygen, chloride ions, etc. in the environment to form a loose oxide film, resulting in local corrosion, such as pitting corrosion and galvanic corrosion. Therefore, it is necessary to improve the corrosion resistance of magnesium-aluminum alloy:

[0003] Traditional magnesium-aluminum alloys rely on main elements (such as Al, Zn) for composition design, lack of synergistic optimization of trace elements, and it is difficult to balance high strength and high corrosion resistance at the same time. Moreover, it is easy to introduce micro-defects, such as pores, shrinkage porosity, segregation, etc. These defects become the starting points of corrosion. Existing processes are difficult to effectively refine grains or optimize composite strengthening phases, resulting in sensitivity to intergranular corrosion. Summary of the Invention

[0004] To solve the above problems, the present invention provides a preparation method of a magnesium-aluminum alloy with high strength and corrosion resistance.

[0005] The present invention provides a preparation method of a magnesium-aluminum alloy with high strength and corrosion resistance, including the following steps:

[0006] Step 1: Heat the aluminum ingot to 800 °C according to the weight parts of a fixed ratio, add zirconium powder and scandium powder, and then stir;

[0007] Then add niobium powder and titanium powder, continue to stir to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at a speed of more than 3000 rpm for solidification, add calcium grains and strontium grains, and continue to stir at a speed of more than 3000 rpm;

[0008] Add C2CL5 agent, refine for 2 h, then let it stand, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0009] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a state of coexistence of solid and liquid phases;

[0010] Then stir at a speed of more than 300 rpm to obtain a semi-solid slurry, and then inject the semi-solid slurry into a preheated mold, and finally cool it to room temperature to obtain a near-net-shaped casting;

[0011] Step 3: Heat the near-net-shaped casting to 440 °C, keep it warm for 12 h, then water quench it to room temperature, then first air cool it at 180 °C for 10 h, and finally air cool it at 120 °C for 24 h to obtain a complete casting;

[0012] Step 4: Immerse the complete casting in the chemical degreasing solution, maintain it at a temperature of 550 °C for 15 minutes, and then rinse it with clean water until the residual degreasing agent on the surface is removed;

[0013] Put the cleaned complete casting into the micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation.

[0014] Preferably, the specific working steps of Step 2 further include the following:

[0015] Set a monitoring period in advance, and obtain the temperature T of the magnesium alloy melt every other period;

[0016] Obtain the ambient temperature T1, ambient humidity RH, ambient air velocity V, and ambient atmospheric pressure P every other period;

[0017] Every other period, according to the formula Calculate and obtain the cooling rate D of the magnesium alloy melt, and the unit of the cooling rate D is °C / min;

[0018] where A is the surface area of the magnesium alloy melt, and the unit is m 2 , ρ is the density of the magnesium alloy melt, and the unit is kg / m 3 , c is the specific heat capacity of the magnesium alloy melt, and the unit is J / (kg·K), V is the volume of the magnesium alloy melt, and the unit is m 3 ;

[0019] where H is the effective heat transfer coefficient and T2 is the dew point temperature;

[0020] Every other period, calculate the power P of the cooling equipment used during the cooling process of the magnesium alloy melt according to the cooling rate D of the magnesium alloy melt, and transmit the calculated power P of the cooling equipment obtained as a signal to the cooling equipment, and adjust the power of the cooling equipment to P.

[0021] Preferably, the specific calculation steps of the effective heat transfer coefficient are as follows:

[0022] According to the formula H = 10*(1 + 0.1*V 0.5 ), calculate and obtain the effective heat transfer coefficient H.

[0023] Preferably, the specific steps of calculating the power P of the cooling equipment used during the cooling process of the magnesium alloy melt according to the cooling rate D of the magnesium alloy melt are as follows:

[0024] Set the reference ambient temperature T3 when the magnesium alloy melt is cooled in advance;

[0025] According to the formula \(P = 5\times e_T+0.1\times\int e_Tdt + 1\times D+0.05\times(T_1 - T_3)\), calculate to obtain the power \(P\) of the adjusted cooling equipment, where \(e_T\) is the difference between the current temperature \(T\) and the target temperature, obtained by subtracting the current temperature \(T\) from the target temperature;

[0026] \(\int e_Tdt\) represents the cumulative value of the temperature deviation over time, that is, the total temperature deviation from the start of control to the current moment.

[0027] Preferably, the steps of step two further include adjusting the rotation speed according to the ambient humidity to inhibit oxidation and ensure rheological properties. The specific steps for adjusting the rotation speed are as follows:

[0028] Obtain the reference rotation speed \(N\) of the magnesium alloy melt stirrer;

[0029] Every other cycle, according to the formula

[0030]

[0031] Calculate to obtain the adjusted rotation speed \(N_t\) of the stirrer, and transmit the calculated stirrer rotation speed \(N_t\) as a signal to the stirrer, and adjust the rotation speed of the cooling equipment to \(N_t\);

[0032] where \(\theta_1\) is the current viscosity of the magnesium alloy melt and \(\theta_2\) is the target viscosity of the magnesium alloy melt.

[0033] Preferably, the working steps of step two further include calculating the loss amount \(\Delta W\) of magnesium content during the process of the magnesium alloy melt becoming a near-net-shaped casting according to the ambient air pressure. The specific steps are as follows:

[0034] Every other cycle, obtain the atmospheric pressure \(P_t\) of the current environment;

[0035] According to the formula \(\Delta W = 0.0011\times(P_t - P)\times t_1\), where \(t_1\) is the exposure time of the magnesium alloy under the current atmospheric pressure \(P_t\), that is, the time of one cycle.

[0036] Preferably, step three further includes dynamically adjusting the solution heat treatment holding time according to the initial state of the casting to ensure that the non-equilibrium phase is completely melted. The specific steps are as follows:

[0037] Every other cycle, obtain the initial residual stress \(M\) and the initial density \(\varphi\) of the near-net-shaped casting;

[0038] Every other cycle, according to the formula Calculate to obtain the dynamically adjusted solution heat treatment holding time \(V_1\), where \(V\) is the holding time of the near-net-shaped casting, which is 12 h, and \(\varphi_1\) is the target density of the near-net-shaped casting set in advance.

[0039] Preferably, the specific preparation steps of the chemical degreasing solution in the fourth step are as follows:

[0040] The chemical degreasing solution specifically includes the following components and mass concentrations: sodium hydroxide 30 - 50 g / L; sodium carbonate 20 - 30 g / L; trisodium phosphate 10 - 20 g / L; sodium silicate 5 - 10 g / L and the balance of water;

[0041] During the preparation process, add about 500 mL of water into a corrosion-resistant container, and then add sodium hydroxide. Since heat is released when sodium hydroxide dissolves, protective gloves and glasses need to be worn. Then add sodium carbonate, trisodium phosphate, and sodium silicate in sequence, stir, and finally add the balance of water to complete the preparation.

[0042] Preferably, the specific preparation steps of the alkaline electrolyte are as follows:

[0043] The alkaline electrolyte specifically includes the following components and mass concentrations: sodium silicate: 20 g / L, sodium hydroxide: 15 g / L, potassium fluoride: 3 g / L, sodium citrate: 1 g / L, triethanolamine: 3 mL / L, and the balance of deionized water;

[0044] During the preparation process, dissolve sodium silicate, sodium hydroxide, potassium fluoride, and sodium citrate in appropriate amounts of deionized water respectively, then add 3 mL / L of triethanolamine, continue to stir, and let the mixed electrolyte stand for 1 hour to complete the preparation.

[0045] Preferably, during the micro-arc oxidation process in the fourth step, the temperature of the electrolyte will rise, and a cooling system needs to be equipped to control the overall temperature. The specific working steps include:

[0046] Install a circulating cooling system in the micro-arc oxidation tank, including a cooling water circulation device and a heat exchanger;

[0047] Before starting micro-arc oxidation, pre-cool the electrolyte to 35 °C to reduce the initial temperature fluctuation;

[0048] Install a temperature sensor in the electrolyte tank to monitor the current temperature of the electrolyte;

[0049] Every other cycle, automatically adjust the cooling power of the cooling system according to the current temperature of the electrolyte to ensure that the electrolyte temperature does not exceed 40 °C;

[0050] The steps to adjust the cooling power of the cooling system are as follows:

[0051] Obtain the temperature rising rate X1 of the electrolyte in the current cycle relative to the previous cycle, and obtain the difference X2 between the target temperature and the current temperature of the electrolyte;

[0052] According to the formula Calculate the cooling power Δτ of the adjusted cooling system, and adjust the power of the cooling system according to the cooling power Δτ of the adjusted cooling system;

[0053] where τ is the total heat of the electrolyte.

[0054] Beneficial effects: By adding trace elements, the strength and corrosion resistance of the magnesium alloy are significantly improved; through vacuum heating and refining treatment, gases and impurities are effectively removed, defects are reduced, the alloy density and melt purity are improved, and its fluidity and formability are better. In the melt treatment stage, by controlling the temperature and stirring, a semi-solid slurry with a coexistence of solid and liquid phases is formed, further improving fluidity and formability, reducing casting defects, and increasing density and strength. During the heat treatment process, through two-stage heating and cooling, high-density nano-precipitation phases are formed, significantly improving the strength and corrosion resistance of the alloy, optimizing the microstructure, and enhancing the comprehensive performance. Finally, through chemical degreasing and micro-arc oxidation treatment, the surface cleanliness of the casting is improved, a dense oxide film is formed, and the corrosion resistance and wear resistance are significantly enhanced. Description of the Drawings

[0055] Figure 1 is a flowchart of the present invention. Detailed Embodiments

[0056] As Figure 1 shown: A preparation method of a magnesium alloy with high strength and corrosion resistance includes the following steps:

[0057] Step 1: Heat the aluminum ingot to 800°C according to the weight parts of a fixed ratio, add zirconium powder and scandium powder, and then stir;

[0058] Then add niobium powder and titanium powder, continue to stir to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at a speed of more than 3000 rpm for solidification, add calcium grains and strontium grains, and continue to stir at a speed of more than 3000 rpm;

[0059] Add C2CL5 agent, refine for 2 hours, then let it stand, skim off the surface scum to obtain a magnesium alloy melt; it should be noted that before preparation, prepare high-purity magnesium ingots (≥99.98%) and high-purity aluminum ingots (≥99.95%), polish the surface of the magnesium ingot to remove the oxide layer, preheat the aluminum ingot to 200°C to remove surface moisture, place the magnesium ingot and aluminum ingot in a vacuum furnace respectively, heat to 400°C (magnesium) and 600°C (aluminum), and keep warm for 1 hour to remove adsorbed gases;

[0060] Step 2: Cool the magnesium alloy melt to 600°C and keep it warm for 10 minutes to form a coexistence state of solid and liquid phases;

[0061] Then, stir at a speed of more than 300 rpm to obtain a semi-solid slurry. Then, inject the semi-solid slurry into a preheated mold and finally cool it to room temperature to obtain a near-net-shaped casting.

[0062] Step 3: Heat the near-net-shaped casting to 440 °C, hold for 12 h, then water quench to room temperature. Then, first air cool at 180 °C for 10 h and finally air cool at 120 °C for 24 h to obtain a complete casting.

[0063] Step 4: Immerse the complete casting in a chemical degreasing solution, maintain at 550 °C for 15 minutes, and then rinse with clean water until the residual degreasing agent on the surface is removed.

[0064] Put the cleaned complete casting into a micro-arc oxidation tank. Add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage at 550 V, the current density at 0.05 A per square decimeter, and the treatment time at 45 minutes to complete the preparation.

[0065] It should be noted that the first stage is 180 °C × 10 h, which is used to form high-density nano-precipitated phases. The second stage is 120 °C × 24 h, which further refines the precipitated phases and improves the strength and corrosion resistance.

[0066] For Step 1, by adding trace elements such as zirconium powder, scandium powder, niobium powder, and titanium powder, the strength and corrosion resistance of the magnesium alloy can be significantly improved. Heating the magnesium ingot and aluminum ingot in a vacuum furnace to 400 °C (magnesium) and 600 °C (aluminum) and holding for 1 hour can effectively remove adsorbed gases, reduce the generation of defects such as porosity and shrinkage porosity, and improve the density of the alloy. Adding a refining agent and performing a 2-hour refining treatment can further remove impurities and gases in the melt, improve the purity of the melt, skim the surface scum after standing for 10 minutes, and the obtained magnesium alloy melt has better fluidity and formability.

[0067] For Step 2, cool the magnesium alloy melt to 600 °C, hold for 8 to 12 minutes to form a solid-liquid two-phase coexistence state with a solid phase ratio of 30% - 40%. The alloy in this state has good fluidity and formability, which can effectively reduce the defects of the casting. Stir at a speed of 300 rpm for 30 minutes to obtain a semi-solid slurry. Inject the semi-solid slurry into a mold preheated to 250 - 300 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 seconds. This process can effectively reduce defects such as porosity and shrinkage porosity of the casting and improve the density and strength of the casting.

[0068] For Step 3, the near-net-shaped casting is heated to 420 - 460 °C, held for 12 hours, and then water-quenched to room temperature. Then it is air-cooled at 180 °C for 10 hours to form high-density nano-precipitates, which can significantly improve the strength and corrosion resistance of the alloy. Finally, it is air-cooled at 120 °C for 24 hours to further refine the precipitates and enhance the strength and corrosion resistance of the alloy. This two-stage heat treatment process can effectively optimize the microstructure of the alloy and improve its comprehensive performance;

[0069] For Step 4, the complete casting is immersed in a chemical degreasing solution and maintained at 500 - 600 °C for 15 minutes, and then rinsed with clean water until the residual degreasing agent on the surface is removed. This step can effectively remove the oil and impurities on the surface of the casting and improve the surface cleanliness. The cleaned complete casting is placed in a micro-arc oxidation tank, an alkaline electrolyte is added, the working voltage is set to 550 V, the current density is 0.05 amperes per square decimeter, and the treatment time is 45 minutes. The micro-arc oxidation treatment can form a dense oxide film on the surface of the casting, significantly improving its corrosion resistance and wear resistance.

[0070] As an optional embodiment: The specific working steps of Step 2 further include the following:

[0071] It should be noted that the magnesium-aluminum alloy melt needs to be precisely cooled from the liquid state (750 - 800 °C) to the semi-solid state range (580 - 600 °C), and the temperature fluctuation needs to be controlled within ±5 °C. Otherwise, it is difficult to stabilize the solid fraction (30% - 40%). Therefore, in the actual use process, the subsequent parameters need to be adjusted in real time according to the temperature of the magnesium-aluminum alloy melt;

[0072] A monitoring period is set in advance, and the temperature T of the magnesium-aluminum alloy melt is obtained every other period;

[0073] It should be noted that the monitoring period is the time interval set in advance, which is in seconds in this embodiment. The monitoring period in this embodiment is 60 seconds;

[0074] It should also be noted that the temperature of the magnesium-aluminum alloy melt can be obtained through a temperature monitoring device, specifically a high-precision thermocouple: inserted into the melt to measure the temperature in real time, and an infrared thermometer is used to obtain it;

[0075] The ambient temperature T1, ambient humidity RH, ambient air velocity V, and ambient atmospheric pressure P are obtained every other period. It should be noted that the above parameters are the parameters in the preparation environment, which are specifically detected by installing corresponding sensors in the workshop;

[0076] Every other period, according to the formula the cooling rate D of the magnesium-aluminum alloy melt is calculated and obtained. The unit of the cooling rate D is °C / min;

[0077] where A is the surface area of the magnesium-aluminum alloy melt, with the unit of m 2 , ρ is the density of the magnesium-aluminum alloy melt, with the unit of kg / m 3 , c is the specific heat capacity of the magnesium-aluminum alloy melt, with the unit of J / (kg·K), and V is the volume of the magnesium-aluminum alloy melt, with the unit of m 3 ; it should be noted that the above parameters are obtained by measurement after the magnesium-aluminum alloy melt is formed. The typical value of the density of the magnesium-aluminum alloy is 1800 kg / m 3 , and the typical value of the specific heat capacity of the magnesium-aluminum alloy is 1000 J / (kg·K);

[0078] where H is the effective heat transfer coefficient and T2 is the dew point temperature; it should be noted that the dew point temperature is closely related to the environmental humidity. The higher the humidity, the closer the dew point temperature is to the environmental temperature. During the cooling process of the melt, if the melt temperature is close to or lower than the dew point temperature, water vapor in the air will condense on the surface of the melt, exacerbating the oxidation reaction and releasing heat, thus affecting the cooling rate;

[0079] It should also be noted that the dew point temperature T2 can be calculated from the environmental temperature T1 and the environmental humidity RH according to the formula and obtained by calculation;

[0080] Every other cycle, the power P of the cooling equipment used in the cooling process of the magnesium-aluminum alloy melt is calculated according to the cooling rate D of the magnesium-aluminum alloy melt, and the calculated power P of the cooling equipment is transmitted as a signal to the cooling equipment, and the power of the cooling equipment is adjusted to P.

[0081] It should be noted that in the actual semi-solid forming process of the magnesium-aluminum alloy, environmental parameters (such as air flow rate, humidity, etc.) have a significant impact on the cooling process of the melt. In this embodiment, by introducing specific environmental parameters, the melt can still be accurately cooled to 580 - 600 °C and the solid fraction is stabilized at 30% - 40% under fluctuating environmental temperatures;

[0082] It should also be noted that by precisely controlling the cooling process of the magnesium-aluminum alloy melt, stable control of the solid fraction is achieved, thereby significantly improving the precision of the preparation process and the stability of product quality. Specifically, by real-time monitoring the melt temperature and dynamically adjusting the power of the cooling equipment according to the temperature change, it is ensured that the melt can accurately cool from the liquid state to the semi-solid state range (580 - 600 °C), and the temperature fluctuation is controlled within ±5 °C, so that the solid fraction is stabilized at 30% - 40%. This process also comprehensively considers the influence of environmental parameters on the melt cooling. By introducing concepts such as the effective heat transfer coefficient and dew point temperature, the control strategy of the cooling process is further optimized, so that the stability and controllability of the melt cooling process can still be maintained under complex environmental conditions. This precise temperature control and environmental parameter monitoring mechanism not only improves the process stability of the magnesium-aluminum alloy semi-solid forming process, but also helps to reduce defects caused by temperature fluctuations and environmental changes, and improves the performance and reliability of the final product.

[0083] As an optional embodiment: The specific calculation steps of the effective heat transfer coefficient are as follows:

[0084] According to the formula H = 10*(1 + 0.1*V 0.5 ), the effective heat transfer coefficient H is calculated and obtained. It should be noted that the purpose of the calculation is to accurately evaluate and predict the heat transfer efficiency of the magnesium-aluminum alloy melt during the cooling process, so as to achieve precise control of the power of the cooling equipment. The effective heat transfer coefficient can reflect the heat exchange ability between the melt and the environment, and helps engineers quantify the heat dissipation rate of the melt under specific environmental conditions.

[0085] As an optional embodiment: The specific steps for calculating the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt are as follows:

[0086] The reference environmental temperature T3 during the cooling of the magnesium-aluminum alloy melt is set in advance; it should be noted that the reference environmental temperature T3 is the ideal state temperature during the cooling of the magnesium-aluminum alloy melt, which is 25 °C in this embodiment;

[0087] According to the formula P = 5*eT + 0.1*∫eTdt + 1*D + 0.05*(T1 - T3), the adjusted power P of the cooling equipment is calculated and obtained, where eT is the difference between the current temperature T and the target temperature, which is obtained by subtracting the current temperature T from the target temperature; it should be noted that the target temperature is 600 °C;

[0088] ∫eTdt represents the cumulative value of the temperature deviation over time, that is, the total temperature deviation from the start of control to the current moment. It should be noted that by analyzing the total temperature deviation, the temperature change trend and law during the cooling process can be understood, so as to optimize the power adjustment strategy of the cooling equipment. For example, if the total temperature deviation continues to increase, it may mean that the current cooling power is insufficient, and the cooling power needs to be increased in time to accelerate the cooling rate; on the contrary, if the total temperature deviation is small and stable, the cooling power can be appropriately reduced to avoid energy waste caused by overcooling.

[0089] As an optional embodiment: The steps of step two further include adjusting the rotation speed according to the ambient humidity to inhibit oxidation and ensure rheological properties. The specific steps of adjusting the rotation speed are as follows:

[0090] Obtain the reference rotation speed N of the magnesium alloy melt stirrer; it should be noted that in this embodiment, the reference rotation speed N is 300 rpm;

[0091] Every other cycle, according to the formula

[0092]

[0093] Calculate and obtain the adjusted stirrer rotation speed Nt, and transmit the calculated stirrer rotation speed Nt as a signal to the stirrer to adjust the rotation speed of the cooling equipment to Nt; it should be noted that by adjusting the rotation speed of the stirrer, it can ensure that various components in the magnesium alloy melt are fully mixed, avoiding local concentration differences, and thus ensuring the uniformity of the material;

[0094] Where θ1 is the current viscosity of the magnesium alloy melt and θ2 is the target viscosity of the magnesium alloy melt.

[0095] It should be noted that the current viscosity is obtained by monitoring with a monitoring device, and the target viscosity is the melt viscosity corresponding to the target solid phase ratio (30% - 40%).

[0096] As an optional embodiment: The working steps of step two further include calculating the magnesium content loss ΔW of the magnesium alloy melt during the process of becoming a near-net-shaped casting according to the ambient air pressure. The specific steps are as follows:

[0097] It should be noted that at low pressure (such as in high-altitude areas), it will cause the volatilization of Mg elements to intensify, resulting in the deviation of the magnesium alloy composition from the design value. This technical solution can calculate and add magnesium ingots at the end of melting according to the current ambient air pressure when the ambient air pressure changes.

[0098] Every other cycle, obtain the current ambient air pressure Pt; it should be noted that the current ambient air pressure Pt is obtained through the corresponding sensor;

[0099] According to the formula ΔW = 0.0011*(Pt - P)*t1, where t1 is the exposure time of the magnesium alloy under the current atmospheric pressure Pt, that is, the time of one cycle.

[0100] As an optional embodiment: Step three further includes dynamically adjusting the solution heat preservation time according to the initial state of the casting to ensure complete melting of the non-equilibrium phase. The specific steps are as follows:

[0101] Every other cycle, obtain the initial residual stress M and the initial density φ of the near-net-shaped casting; it should be noted that the initial density of the casting can be obtained by non-destructive testing techniques (such as ultrasonic testing, X-ray testing, etc.) or physical measurement methods (such as density measurement), and the initial residual stress of the casting can be obtained by residual stress measurement techniques (such as X-ray diffraction method, blind hole method, etc.);

[0102] Every other cycle, according to the formula Calculate the dynamically adjusted solution heat preservation time V1, where V is the heat preservation time of the near-net-shaped casting, which is 12h, and φ1 is the target density of the near-net-shaped casting set in advance. It should be noted that in this embodiment, the target density is 98%.

[0103] As an optional embodiment: The specific preparation steps of the chemical degreasing solution in step four are as follows:

[0104] The chemical degreasing solution specifically includes the following components and mass concentrations: sodium hydroxide 30 - 50g / L; sodium carbonate 20 - 30g / L; trisodium phosphate 10 - 20g / L; sodium silicate 5 - 10g / L and the balance of water;

[0105] During the configuration process, add about 500 mL of water to a corrosion-resistant container, and then add sodium hydroxide. Since heat is released when sodium hydroxide dissolves, protective gloves and glasses need to be worn. Then add sodium carbonate, trisodium phosphate, and sodium silicate in sequence, stir, and finally add the balance of water to complete the configuration.

[0106] It should be noted that through the treatment of the chemical degreasing solution, the surface of the casting can reach a high cleanliness, creating good conditions for the subsequent micro-arc oxidation treatment. If there are impurities such as oil stains on the surface of the casting, it will affect the formation quality and bonding force of the oxide film during micro-arc oxidation, resulting in uneven, loose oxide film, or even problems such as peeling. The chemical degreasing solution can thoroughly remove the surface oil stains, ensuring that the oxide film can be formed evenly and densely on the surface of the casting during micro-arc oxidation, improving the corrosion resistance and wear resistance of the casting.

[0107] As an optional embodiment: The specific preparation steps of the alkaline electrolyte are as follows:

[0108] The alkaline electrolyte specifically includes the following components and mass concentrations: sodium silicate: 20 g / L, sodium hydroxide: 15 g / L, potassium fluoride: 3 g / L, sodium citrate: 1 g / L, triethanolamine: 3 mL / L, and the balance deionized water;

[0109] During the preparation process, sodium silicate, sodium hydroxide, potassium fluoride, and sodium citrate are respectively dissolved in an appropriate amount of deionized water, then 3 mL / L of triethanolamine is added, and stirring is continued. The mixed electrolyte is allowed to stand for 1 hour to complete the preparation. It should be noted that during the micro-arc oxidation process, the alkaline electrolyte serves as the medium for the electrolytic reaction, providing an environment for ionic conduction, enabling the current to pass through the electrolyte smoothly, and an oxidation reaction occurs on the surface of the magnesium alloy to form an oxide film. Various components in the electrolyte will undergo electrochemical reactions during the electrolysis process, generating some intermediate products and final products, and these products will participate in the formation process of the oxide film, affecting the composition, structure, and properties of the oxide film. For example, sodium hydroxide will participate in the formation of hydroxide ions during the electrolysis process, and these ions will react with metal ions such as magnesium and aluminum to form corresponding hydroxide precipitates, which are further converted into oxides and become part of the oxide film.

[0110] As an optional embodiment: During the micro-arc oxidation process in step four, the temperature of the electrolyte will increase, and a cooling system needs to be equipped to control the overall temperature. The specific working steps include:

[0111] Install a circulating cooling system in the micro-arc oxidation tank, including a cooling water circulation device and a heat exchanger;

[0112] Before starting the micro-arc oxidation, pre-cool the electrolyte to 35 °C to reduce the initial temperature fluctuation;

[0113] Install a temperature sensor in the electrolyte tank to monitor the current temperature of the electrolyte;

[0114] Every other cycle, automatically adjust the cooling power of the cooling system according to the current temperature of the electrolyte to ensure that the electrolyte temperature does not exceed 40 °C;

[0115] The steps to adjust the cooling power of the cooling system are as follows:

[0116] Obtain the temperature rise rate X1 of the electrolyte in the current cycle relative to the previous cycle, and obtain the difference X2 between the target temperature and the current temperature of the electrolyte;

[0117] According to the formula Calculate the adjusted cooling power Δτ of the cooling system, and adjust the power of the cooling system according to the adjusted cooling power Δτ of the cooling system;

[0118] where τ is the total heat of the electrolyte. It should be noted that through the above method, the temperature and cooling rate of the electrolyte can be effectively controlled, thereby ensuring the stability of the micro-arc oxidation process and the quality of the coating.

[0119] Working principle:

[0120] By adding trace elements, the strength and corrosion resistance of the magnesium-aluminum alloy are significantly improved; through vacuum heating and refining treatment, gases and impurities are effectively removed, defects are reduced, the alloy density and melt purity are increased, and its fluidity and formability are better. In the melt treatment stage, by controlling the temperature and stirring, a semi-solid slurry with coexisting solid and liquid phases is formed, further improving fluidity and formability, reducing casting defects, and increasing density and strength. During the heat treatment process, through two-stage heating and cooling, high-density nano-precipitates are formed, significantly improving the strength and corrosion resistance of the alloy, optimizing the microstructure, and enhancing the comprehensive performance. Finally, through chemical degreasing and micro-arc oxidation treatment, the surface cleanliness of the casting is improved, a dense oxide film is formed, and the corrosion resistance and wear resistance are significantly enhanced.

[0121] The following is a further description based on specific embodiments:

[0122] Example 1:

[0123] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0124] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue stirring for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue stirring at 3000 rpm for 20 min;

[0125] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0126] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and hold for 10 min to form a coexisting state of solid and liquid phases;

[0127] Then stir at 300 rpm for 30 min to obtain a semi-solid slurry, and then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s, and finally cool to room temperature to obtain a near-net-shaped casting;

[0128] Step 3: Heat the near-net-shaped casting to 440 °C, hold for 12 h, then water-quench to room temperature, and then first air-cool at 180 °C for 10 h, and finally air-cool at 120 °C for 24 h to obtain a complete casting;

[0129] Step 4: Immerse the complete casting in a chemical degreasing solution, maintain it at a temperature of 550 °C for 15 minutes, and then rinse it with clean water until the residual degreasing agent on the surface is removed;

[0130] Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0131] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P;

[0132] In the above Step 2, it also includes adjusting the rotation speed according to the ambient humidity to inhibit oxidation and ensure rheological properties;

[0133] In the above Step 2, it also includes calculating the loss amount ΔW of magnesium content of the magnesium-aluminum alloy melt during the process of becoming a near-net-shaped casting according to the ambient air pressure;

[0134] In the above Step 3, it also includes dynamically adjusting the solution heat treatment holding time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved;

[0135] The chemical degreasing solution in the above Step 4 specifically includes the following components and mass concentrations: sodium hydroxide 30 g / L; sodium carbonate 20 g / L; trisodium phosphate 10 g / L; sodium silicate 5 g / L and the balance of water;

[0136] Example 2:

[0137] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0138] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue to stir at a speed of 3000 rpm for 20 min;

[0139] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let it stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0140] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and hold for 10 min to form a solid-liquid two-phase coexistence state;

[0141] Then, stir at a rotational speed of 300 rpm for 30 minutes to obtain a semi-solid slurry. Then, inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s. Finally, cool it to room temperature to obtain a near-net-shaped casting;

[0142] Step 3: Heat the near-net-shaped casting to 440 °C, hold for 12 h, then water quench to room temperature. Then, first air cool at 180 °C for 10 h, and finally air cool at 120 °C for 24 h to obtain a complete casting;

[0143] Step 4: Immerse the complete casting in a chemical degreasing solution, maintain at 500 - 600 °C for 15 minutes, and then rinse with clean water until the residual degreasing agent on the surface is removed;

[0144] Put the cleaned complete casting into a micro-arc oxidation tank. Add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 A per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0145] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P;

[0146] In the above Step 2, it also includes adjusting the rotational speed according to the environmental humidity to inhibit oxidation and ensure rheological properties;

[0147] In the above Step 2, it also includes calculating the magnesium content loss ΔW of the magnesium-aluminum alloy melt during the process of becoming a near-net-shaped casting according to the environmental air pressure;

[0148] In the above Step 3, it also includes dynamically adjusting the solution holding time according to the initial state of the casting to ensure complete dissolution of non-equilibrium phases;

[0149] The chemical degreasing solution in the above Step 4 specifically includes the following components and mass concentrations: sodium hydroxide 40 g / L; sodium carbonate 25 g / L; trisodium phosphate 15 / L; sodium silicate 7.5 g / L and the balance of water;

[0150] Example 3:

[0151] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0152] Add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, and continue stirring for 30 min to form an intermediate alloy melt. Pour the melt into a rotating copper roller, and stir at 3000 rpm for 30 min for solidification. Add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue stirring at 3000 rpm for 20 min;

[0153] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let it stand for 10 min, and skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0154] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a state of coexistence of solid and liquid phases;

[0155] Then stir at 300 rpm for 30 min to obtain a semi-solid slurry. Then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s. Finally, cool it to room temperature to obtain a near-net-shaped casting;

[0156] Step 3: Heat the near-net-shaped casting to 440 °C, keep it warm for 12 h, then water-quench it to room temperature, then air-cool it at 180 °C for 10 h first, and finally air-cool it at 120 °C for 24 h to obtain a complete casting;

[0157] Step 4: Immerse the complete casting in a chemical degreasing solution, maintain it at a temperature of 500 - 600 °C for 15 minutes, and then rinse it with clean water until the residual degreasing agent on the surface is removed;

[0158] Put the cleaned complete casting into a micro-arc oxidation tank. Add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0159] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P;

[0160] In the above Step 2, it also includes adjusting the rotation speed according to the environmental humidity to inhibit oxidation and ensure rheological properties;

[0161] In the above Step 2, it also includes calculating the magnesium content loss ΔW of the magnesium-aluminum alloy melt during the process of becoming a near-net-shaped casting according to the environmental air pressure;

[0162] In the above Step 3, it also includes dynamically adjusting the solution heat preservation time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved;

[0163] The chemical degreasing solution in the above step four specifically includes the following components and mass concentrations: sodium hydroxide 50 g / L; sodium carbonate 30 g / L; trisodium phosphate 20 / L; sodium silicate 10 g / L and the balance water;

[0164] Example 4:

[0165] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0166] Add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roll, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue to stir at 3000 rpm for 20 min;

[0167] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0168] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a state of coexistence of solid and liquid phases;

[0169] Then stir at a speed of 300 rpm for 30 min to obtain a semi-solid slurry, and then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s, and finally cool to room temperature to obtain a near-net-shaped casting;

[0170] Step 3: Heat the near-net-shaped casting to 440 °C, keep it warm for 12 h, then water-quench to room temperature, then first air-cool at 180 °C for 10 h, and finally air-cool at 120 °C for 24 h to obtain a complete casting;

[0171] Step 4: Immerse the complete casting in the chemical degreasing solution, maintain at a temperature of 500 - 600 °C for 15 minutes, and then rinse with clean water until the residual degreasing agent on the surface is removed;

[0172] Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0173] In the above step two, it includes adjusting the rotation speed according to the environmental humidity to inhibit oxidation and ensure rheological properties;

[0174] In the above step two, it also includes calculating the loss amount ΔW of the magnesium content in the magnesium-aluminum alloy melt during the process of becoming a near-net-shaped casting according to the environmental air pressure;

[0175] In the above step 3, it also includes dynamically adjusting the solution heat preservation time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved;

[0176] The chemical degreasing solution in the above step 4 specifically includes the following components and mass concentrations: sodium hydroxide 50 g / L; sodium carbonate 30 g / L; trisodium phosphate 20 / L; sodium silicate 10 g / L and the balance of water;

[0177] Example 5:

[0178] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0179] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue to stir at 3000 rpm for 20 min;

[0180] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0181] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a solid-liquid two-phase coexistence state;

[0182] Then stir at 300 rpm for 30 min to obtain a semi-solid slurry, and then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s, and finally cool to room temperature to obtain a near-net-shaped casting;

[0183] Step 3: Heat the near-net-shaped casting to 440 °C, keep it warm for 12 h, then water-quench to room temperature, then first air-cool at 180 °C for 10 h, and finally air-cool at 120 °C for 24 h to obtain a complete casting;

[0184] Step 4: Immerse the complete casting in the chemical degreasing solution, maintain at a temperature of 500 - 600 °C for 15 minutes, and then rinse with clean water until the residual degreasing agent on the surface is removed;

[0185] Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0186] In the above step 2, every other cycle, the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt is calculated according to the cooling rate D of the magnesium-aluminum alloy melt, and the calculated power P of the cooling equipment is transmitted as a signal to the cooling equipment to adjust the power of the cooling equipment to P;

[0187] In the above step 2, it also includes calculating the loss amount ΔW of magnesium content during the process of the magnesium-aluminum alloy melt becoming a near-net-shaped casting according to the ambient air pressure;

[0188] In the above step 3, it also includes dynamically adjusting the solution heat treatment holding time according to the initial state of the casting to ensure that the non-equilibrium phases are completely dissolved;

[0189] The chemical degreasing solution in the above step 4 specifically includes the following components and mass concentrations: sodium hydroxide 50 g / L; sodium carbonate 30 g / L; trisodium phosphate 20 / L; sodium silicate 10 g / L and the balance of water;

[0190] Example 6:

[0191] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0192] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue to stir at 3000 rpm for 20 min;

[0193] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0194] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and hold for 10 min to form a solid-liquid two-phase coexistence state;

[0195] Then stir at a speed of 300 rpm for 30 min to obtain a semi-solid slurry, and then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s, and finally cool to room temperature to obtain a near-net-shaped casting;

[0196] Step 3: Heat the near-net-shaped casting to 440 °C, hold for 12 h, then water quench to room temperature, then first air cool at 180 °C for 10 h, and finally air cool at 120 °C for 24 h to obtain a complete casting;

[0197] Step 4: Immerse the complete casting in a chemical degreasing solution and maintain it at a temperature of 500 - 600 °C for 15 minutes, then rinse it with clean water until the residual degreasing agent on the surface is removed;

[0198] Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0199] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P;

[0200] In the above Step 2, it also includes adjusting the rotation speed according to the ambient humidity to inhibit oxidation and ensure rheological properties;

[0201] In the above Step 3, it also includes dynamically adjusting the solution heat preservation time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved;

[0202] The chemical degreasing solution in the above Step 4 specifically includes the following components and mass concentrations: sodium hydroxide 50 g / L; sodium carbonate 30 g / L; trisodium phosphate 20 / L; sodium silicate 10 g / L and the balance of water;

[0203] Example 7:

[0204] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0205] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium grains and 0.075 parts by weight of strontium grains, and continue to stir at 3000 rpm for 20 min;

[0206] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let it stand for 10 min, skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0207] Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a solid-liquid two-phase coexistence state;

[0208] Then stir at a rotation speed of 300 rpm for 30 min to obtain a semi-solid slurry, and then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s, and finally cool to room temperature to obtain a near-net-shaped casting;

[0209] Step 3: Heat the near-net-shaped casting to 440 °C, hold for 12 h, then water quench to room temperature, then air cool at 180 °C for 10 h, and finally air cool at 120 °C for 24 h to obtain a complete casting;

[0210] Step 4: Immerse the complete casting in a chemical degreasing solution, maintain at 500 - 600 °C for 15 minutes, then rinse with clean water until the residual degreasing agent on the surface is removed;

[0211] Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation;

[0212] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P;

[0213] In the above Step 2, it also includes adjusting the rotation speed according to the environmental humidity to inhibit oxidation and ensure rheological properties;

[0214] In the above Step 2, it also includes calculating the magnesium content loss ΔW of the magnesium-aluminum alloy melt during the process of becoming a near-net-shaped casting according to the environmental air pressure;

[0215] The chemical degreasing solution in the above Step 4 specifically includes the following components and mass concentrations: sodium hydroxide 50 g / L; sodium carbonate 30 g / L; trisodium phosphate 20 / L; sodium silicate 10 g / L and the balance of water;

[0216] Example 8:

[0217] Step 1: Heat 6.5 parts by weight of aluminum ingots to 800 °C, add 0.75 parts by weight of zirconium powder and 0.4 parts by weight of scandium powder, and then stir;

[0218] Then add 0.3 parts by weight of niobium powder and 0.15 parts by weight of titanium powder, continue to stir for 30 min to form an intermediate alloy melt, pour the melt into a rotating copper roller, stir at 3000 rpm for 30 min for solidification, add 0.2 parts by weight of calcium granules and 0.075 parts by weight of strontium granules, and continue to stir at 3000 rpm for 20 min;

[0219] Add 0.25 parts by weight of C2CL5 agent, refine for 2 h, then let stand for 10 min, and skim off the surface scum to obtain a magnesium-aluminum alloy melt;

[0220] Step 2: Cool the magnesium alloy melt to 600 °C and hold for 10 min to form a state of coexistence of solid and liquid phases;

[0221] Then stir at a rotation speed of 300 rpm for 30 min to obtain semi-solid slurry. Then inject the semi-solid slurry into a mold preheated to 275 °C, with a die-casting pressure of 100 MPa and a holding pressure time of 12 s. Finally, cool to room temperature to obtain a near-net-shaped casting;

[0222] Step 3: Heat the near-net-shaped casting to 440 °C and hold for 12 h, then water quench to room temperature. Then first air cool at 180 °C for 10 h, and finally air cool at 120 °C for 24 h to obtain a complete casting;

[0223] In the above Step 2, every other cycle, calculate the power P of the cooling equipment used during the cooling process of the magnesium alloy melt according to the cooling rate D of the magnesium alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment to adjust the power of the cooling equipment to P;

[0224] In the above Step 2, it also includes adjusting the rotation speed according to the environmental humidity to inhibit oxidation and ensure rheological properties;

[0225] In the above Step 2, it also includes calculating the loss amount ΔW of magnesium content during the process of the magnesium alloy melt becoming a near-net-shaped casting according to the environmental air pressure;

[0226] In the above Step 3, it also includes dynamically adjusting the solution heat treatment holding time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved;

[0227] Perform performance tests on the magnesium alloy prepared in the above examples. The specific test method is

[0228] Immerse the specimens in acid solutions of the same concentration at different time points such as 1 day, 3 days, and 7 days, observe the corrosion conditions of the specimens. The test results are shown in the following table:

[0229]

[0230] Among them, Example 1, Example 2 and Example 3 are roughly the same, except that the formulations of the chemical degreasing solutions are different. Based on the comparison of Example 1, Example 2 and Example 3, it can be obtained that Example 3 can meet the requirements for the percentage range of the composition quality of the chemical degreasing solution composition. The chemical degreasing solution prepared based on the composition quality of this mosquito and fly attractant combination has good degreasing effects;

[0231] Example 4 is substantially the same as Example 3, except that in Example 4, the steps in Step 2 are reduced by calculating the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt every other cycle according to the cooling rate D of the magnesium-aluminum alloy melt, and transmitting the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjusting the power of the cooling equipment to P. By comparison, the properties of the magnesium-aluminum alloy prepared under different processes can be obtained;

[0232] Example 5 is substantially the same as Example 3, except that in Example 5, the steps in Step 2 are reduced by further including the step of adjusting the rotation speed according to the environmental humidity to inhibit oxidation and ensure rheological properties. By comparison, the properties of the magnesium-aluminum alloy prepared under different processes can be obtained;

[0233] Example 6 is substantially the same as Example 3, except that in Example 6, the steps in Step 2 are reduced by further including the step of calculating the loss amount ΔW of magnesium content during the process of the magnesium-aluminum alloy melt becoming a near-net-shaped casting according to the environmental air pressure. By comparison, the properties of the magnesium-aluminum alloy prepared under different processes can be obtained;

[0234] Example 7 is substantially the same as Example 3, except that in Example 7, the steps in Step 2 are reduced by further including the step of dynamically adjusting the solution heat treatment holding time according to the initial state of the casting to ensure complete melting of the non-equilibrium phase. By comparison, the properties of the magnesium-aluminum alloy prepared under different processes can be obtained;

[0235] Example 8 is substantially the same as Example 3, except that Step 4 is removed in Example 8. By comparison, the properties of the magnesium-aluminum alloy prepared under different processes can be obtained;

[0236] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of this template.

Claims

1. A preparation method of a magnesium-aluminum alloy with high corrosion resistance, characterized in that It includes the following steps: Step 1: Heat the aluminum ingot to 800 °C according to the weight parts of a fixed ratio, add zirconium powder and scandium powder, and then stir; Add niobium powder and titanium powder, continue to stir to form an intermediate alloy melt, pour the melt into a rotating copper roll, stir at a speed of more than 3000 rpm for solidification, add calcium grains and strontium grains, and continue to stir at a speed of more than 3000 rpm; Additive amount Add the agent, refine for 2 h, then let it stand, skim off the surface scum to obtain the magnesium-aluminum alloy melt; Step 2: Cool the magnesium-aluminum alloy melt to 600 °C and keep it warm for 10 min to form a state of coexistence of solid and liquid phases; Then stir at a speed of more than 300 rpm to obtain a semi-solid slurry, inject the semi-solid slurry into a preheated mold, and finally cool it to room temperature to obtain a near-net-shaped casting; Step 3: Heat the near-net-shaped casting to 440 °C, keep it warm for 12 h, then water-quench it to room temperature, then air-cool it at 180 °C for 10 h first, and finally air-cool it at 120 °C for 24 h to obtain a complete casting; Step 4: Immerse the complete casting in a chemical degreasing solution, maintain it at 550 °C for 15 minutes, and then rinse it with clean water until the residual degreasing agent on the surface is removed; Put the cleaned complete casting into a micro-arc oxidation tank, add an alkaline electrolyte to the micro-arc oxidation tank, set the working voltage to 550 V, the current density to 0.05 amperes per square decimeter, and the treatment time to 45 minutes to complete the preparation.

2. The preparation method of a magnesium-aluminum alloy with high strength and corrosion resistance according to claim 1, characterized in that the specific working steps of step 2 further include the following: Set a monitoring period in advance, and obtain the temperature T of the magnesium-aluminum alloy melt every other period; Obtain the ambient temperature T1, ambient humidity RH, ambient air velocity V and ambient atmospheric pressure P every other period; Every other cycle, according to the formula , the cooling rate D of the magnesium-aluminum alloy melt is calculated and obtained. The unit of the cooling rate D is °C / min; where A is the surface area of the magnesium-aluminum alloy melt, with the unit of m², is the density of the magnesium-aluminum alloy melt, with the unit of kg / m³, c is the specific heat capacity of the magnesium-aluminum alloy melt, with the unit of J / (kg·K), and V is the volume of the magnesium-aluminum alloy melt, with the unit of m³; where H is the effective heat transfer coefficient and T2 is the dew point temperature; Every other period, calculate the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt, and transmit the calculated power P of the cooling equipment as a signal to the cooling equipment, and adjust the power of the cooling equipment to P.

3. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 2, characterized in that, The specific calculation steps of the effective heat transfer coefficient are as follows: According to the formula , the effective heat transfer coefficient H is calculated and obtained.

4. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 2, characterized in that, The specific steps of calculating the power P of the cooling equipment used during the cooling process of the magnesium-aluminum alloy melt according to the cooling rate D of the magnesium-aluminum alloy melt are as follows: Set a reference ambient temperature T3 when the magnesium-aluminum alloy melt is cooled in advance; According to the formula , calculate and obtain the power P of the adjusted cooling device, where is the difference between the current temperature T and the target temperature, obtained by subtracting the current temperature T from the target temperature; Represents the cumulative value of the temperature deviation over time, that is, the total sum of the temperature deviations from the start of control to the current moment.

5. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 2, characterized in that The steps of step 2 also include adjusting the rotation speed according to the ambient humidity to inhibit oxidation and ensure rheological properties. The specific steps of adjusting the rotation speed are as follows: Obtain the reference rotation speed N of the stirrer of the magnesium-aluminum alloy melt; Every other period, according to the formula Calculate and obtain the adjusted agitator speed , and transmit the calculated agitator speed as a signal to the agitator, and adjust the speed of the cooling equipment to ; wherein is the current viscosity of the magnesium-aluminum alloy melt, is the target viscosity of the magnesium-aluminum alloy melt.

6. The preparation method of a high-strength corrosion-resistant magnesium alloy according to claim 2, characterized in that, The working steps of the second step further include calculating the loss amount of magnesium content in the magnesium alloy melt during the process of becoming a near-net-shaped casting according to the ambient air pressure , and the specific steps are as follows: Obtain the atmospheric pressure Pt of the current environment every other period; According to the formula , where t1 is the exposure time of the magnesium-aluminum alloy under the current atmospheric pressure Pt, that is, the time of one cycle.

7. A preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 1, characterized in that, Step 3 also includes dynamically adjusting the solution heat preservation time according to the initial state of the casting to ensure that the non-equilibrium phase is completely dissolved. The specific steps are: Obtain the initial residual stress M and the initial density of the near-net-shaped casting every other cycle ; Every other cycle, according to the formula , the dynamically adjusted solution heat treatment holding time V1 is calculated, where V is the holding time of the nearly formed casting, which is 12 h, is the target density of the nearly formed casting set in advance.

8. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 1, characterized in that, The specific preparation steps of the chemical deoxidizing solution in step 4 include the following: The chemical degreasing solution specifically includes the following components and mass concentrations: sodium hydroxide 30 - 50 g / L; sodium carbonate 20 - 30 g / L; trisodium phosphate 10 - 20 g / L; sodium silicate 5 - 10 g / L and the balance of water; During the configuration process, add approximately 500 mL of water to a corrosion-resistant container, and then add sodium hydroxide. Since heat is released when sodium hydroxide dissolves, protective gloves and glasses should be worn. Then, add sodium carbonate, trisodium phosphate, and sodium silicate in sequence, stir, and finally add the remaining water to complete the configuration.

9. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 1, characterized in that, The specific preparation steps of the alkaline electrolyte are as follows: The alkaline electrolyte specifically includes the following components and mass concentrations: sodium silicate: 20 g / L, sodium hydroxide: 15 g / L, potassium fluoride: 3 g / L, sodium citrate: 1 g / L, triethanolamine: 3 mL / L, and the remaining deionized water; During the configuration process, dissolve sodium silicate, sodium hydroxide, potassium fluoride, and sodium citrate in appropriate amounts of deionized water respectively, then add 3 mL / L of triethanolamine, continue to stir, and let the mixed electrolyte stand for 1 hour to complete the configuration.

10. The preparation method of a magnesium-aluminum alloy with high corrosion resistance according to claim 1, characterized in that, During the micro-arc oxidation process in step 4, the temperature of the electrolyte will rise, and a cooling system needs to be equipped to control the overall temperature. The specific working steps include: Install a circulating cooling system in the micro-arc oxidation tank, including a cooling water circulation device and a heat exchanger; Before starting micro-arc oxidation, pre-cool the electrolyte to 35 °C to reduce the initial temperature fluctuation; Install a temperature sensor in the electrolyte tank to monitor the current temperature of the electrolyte; Every other cycle, automatically adjust the cooling power of the cooling system according to the current temperature of the electrolyte to ensure that the electrolyte temperature does not exceed 40 °C; The steps to adjust the cooling power of the cooling system are as follows: Obtain the temperature rise rate X1 of the electrolyte in the current cycle relative to the previous cycle, and obtain the difference X2 between the target temperature and the current temperature of the electrolyte; According to the formula , the cooling power of the adjusted cooling system is calculated , and the power of the cooling system is adjusted according to the cooling power of the adjusted cooling system ; Among them is the total heat of the electrolyte solution.

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