Refining and purifying method for cast aluminum alloy liquid

Abstract

The invention discloses a refining and purifying method for cast aluminum alloy liquid, which comprises the following steps: firstly, carrying out blowing refining and deslagging treatment on the cast aluminum alloy liquid by using inert gas and a solid powder refining agent, then carrying out blowing refining and dehydrogenation treatment on the cast aluminum alloy liquid by using mixed gas, and carrying out slagging-off and standing to obtain the high-cleanliness cast aluminum alloy liquid. According to the method, powder refining agent injection refining and mixed gas injection refining are combined, so that deep refining purification treatment of the cast aluminum alloy liquid is realized, the harm of air holes and inclusions to the mechanical property of the cast aluminum alloy is eliminated, and the contradictory problem of mutual restriction between strength and plasticity is solved; and the strength and plasticity of the cast aluminum alloy part are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy purification, and in particular relates to a refining and purification method for casting aluminum alloy liquid. Background Art

[0002] Cast aluminum alloy is an aluminum alloy with aluminum and silicon as the main elements. It has good casting performance, corrosion resistance and mechanical properties. It is widely used in casting various load-bearing aluminum alloy structural parts, such as automobile steering knuckles, brake calipers, control arms, engine cylinders, cylinder heads, pistons, wheels, etc. With the development of lightweight and integrated die-casting of new energy vehicles, the requirements for the mechanical properties of cast aluminum alloys are getting higher and higher, requiring both higher strength and good plasticity to meet the manufacturing requirements of lightweight development and integrated die-casting of new energy vehicles.

[0003] The mechanical properties of cast aluminum alloys are related to their composition. The strength of cast aluminum alloys can usually be improved by increasing the content or amount of strengthening elements, but this method will also lead to a decrease in the plasticity of cast aluminum alloys. The reason is that there is a contradiction between the strength and plasticity of cast aluminum alloys, which restrict each other and increase while the other decreases.

[0004] The mechanical properties of cast aluminum alloys are also related to their organizational state. Coarse α-Al grains, Si phases and Fe-rich phases will reduce the strength and plasticity of cast aluminum alloys, while fine and uniform α-Al grains, Si phases and Fe-rich phases can improve the strength and plasticity of cast aluminum alloys. Therefore, refining and modifying cast aluminum alloys is also an effective way to improve strength and plasticity.

[0005] Pores and inclusions are common defects in cast aluminum alloys. Pores and inclusions will split the matrix of cast aluminum alloys, destroy the organizational continuity of cast aluminum alloys, cause local stress concentration, and become the crack source and crack extension direction of cast aluminum alloy fracture, thereby reducing the strength and plasticity of cast aluminum alloys. Therefore, refining, degassing and deslagging the cast aluminum alloy liquid and improving the cleanliness of the cast aluminum alloy can simultaneously improve the strength and plasticity of the cast aluminum alloy, which is an effective way to solve the mutual restriction between the strength and plasticity of cast aluminum alloys.

[0006] The existing refining and purification technologies for cast aluminum alloy liquid mainly include powder spraying refining and ventilation refining. The powder spraying refining uses an inert gas as a carrier to spray a solid powdered refining agent into the cast aluminum alloy liquid, and the refining agent captures and absorbs the inclusions in the cast aluminum alloy liquid, and then floats them out to achieve the purpose of slag removal. The ventilation refining is to pass inert gas nitrogen or argon into the cast aluminum alloy liquid, and the hydrogen in the cast aluminum alloy liquid is adsorbed and taken out by the inert gas bubbles to achieve the purpose of degassing.

[0007] From the results of literature retrieval and production practice, it can be seen that the existing refining and purification technology has low degassing and slag removal efficiency, which cannot significantly improve the cleanliness of cast aluminum alloy liquid, and still cannot solve the contradiction between the strength and plasticity of cast aluminum alloy, and cannot meet the production needs of high-strength and high-plasticity cast aluminum alloy. Therefore, the existing refining and purification technology of cast aluminum alloy liquid still needs to be improved and developed. Summary of the invention

[0008] In view of the problems and shortcomings of the background technology, the purpose of the present invention is to provide a refining and purification method for casting aluminum alloy liquid, which can significantly reduce the gas slag content of the casting aluminum alloy liquid, improve the cleanliness of the casting aluminum alloy, solve the problem of mutual restriction between strength and plasticity, and improve the strength and plasticity of the casting aluminum alloy.

[0009] The technical solution adopted by the present invention to achieve the above-mentioned purpose is as follows:

[0010] A method for refining and purifying cast aluminum alloy liquid, characterized in that it comprises the following steps in sequence:

[0011] Step 1: Use inert gas and solid powder refining agent to spray and refine the cast aluminum alloy liquid to remove slag, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for a period of time;

[0012] Step 2: Use mixed gas to spray, refine and remove hydrogen from the cast aluminum alloy liquid, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for a period of time to obtain a highly clean cast aluminum alloy liquid.

[0013] Preferably, the inert gas in step one is argon with a purity of ≥99.99%, the amount of the refining agent is 0.1-0.2% of the weight of the cast aluminum alloy liquid, the temperature of the cast aluminum alloy liquid during the spray refining is 700-720°C, the spray refining time is 15-25 minutes, and the standing time of the cast aluminum alloy liquid is 30-40 minutes.

[0014] The spray refining adopts a powder spray tank and a metal tube, uses an inert gas as a carrier, and sprays a solid powder refining agent into the casting aluminum alloy liquid, so that the refining agent and the casting aluminum alloy liquid are fully contacted and reacted, and then the inclusions in the casting aluminum alloy liquid are taken out of the aluminum alloy liquid to achieve the purpose of slag removal.

[0015] The deslagging effect of spray refining is related to process parameters such as the purity of the inert gas, the amount of refining agent, the quality of the refining agent, the temperature of the cast aluminum alloy liquid and the spray refining time. The inert gas can be argon or nitrogen. Since nitrogen will react with the cast aluminum alloy liquid to form aluminum nitride, it will not only cause aluminum loss, but also leave aluminum nitride in the aluminum slag. When the aluminum slag encounters water, aluminum nitride will react with water to produce irritating and unpleasant ammonia, causing environmental pollution and harming human health. Therefore, the inert gas is preferably argon. The higher the purity of argon, the better. In order to ensure the deslagging effect of spray refining and avoid the introduction of water vapor to cause the cast aluminum alloy liquid to absorb hydrogen, argon with a purity of ≥99.99% is preferred.

[0016] The greater the amount of refining agent used, the longer the spray refining time, the better the deslagging effect of spray refining, but the corresponding production cost will also increase. However, if the temperature of the cast aluminum alloy liquid is too high or the spray refining time is too long, the oxidation and burning of the aluminum alloy liquid will also increase. Preferably, the amount of refining agent used is 0.1-0.2% of the weight of the cast aluminum alloy liquid, the temperature of the cast aluminum alloy liquid is 700-720°C, and the spray refining time is 15-25 minutes. After the spray refining is completed and the scum on the surface of the cast aluminum alloy liquid is removed, a covering agent should be sprinkled on the surface of the cast aluminum alloy liquid in time to avoid oxidation and burning of the cast aluminum alloy liquid and hydrogen absorption.

[0017] Preferably, the refining agent in step 1 is composed of the following components in percentage by mass: NaCl 35.12%, NaF 19.84%, TiCl 3 16.51%, SrSO 4 10.06%, KPO 3 11.45%, Na 2 B 4 O 7 7.02%.

[0018] The deslagging effect of powder refining is closely related to the composition of the refining agent. Existing refining agents are mainly obtained by crushing and mixing fluoride salts and chloride salts. The deslagging efficiency of refining agents is low, and there are also problems such as large irritating smoke emissions and single functions. It is difficult to meet the production needs of high-cleanliness and high-performance cast aluminum alloys.

[0019] In order to improve the deslagging efficiency of powder spray refining, the present invention has developed a more efficient and environmentally friendly multifunctional refining agent, in which NaCl reacts with aluminum liquid to generate AlCl with a boiling point of only 180°C. 3 , AlCl 3 During the floating process, the bubbles absorb and capture inclusions and escape from the aluminum liquid together, thus playing a role in slag removal.

[0020] NaF molten salt can destroy the alumina film, dissolve inclusions such as alumina into the molten salt, increase the surface tension between the inclusions and the aluminum liquid, promote the separation of inclusions such as alumina from the aluminum liquid, and enhance the slag removal function of the refining agent.

[0021] TiCl 3 The Ti element generated by the reaction with the aluminum liquid directly enters the aluminum liquid, which can refine the α-Al grains of the aluminum alloy and improve the strength and plasticity of the cast aluminum alloy. 3 During the floating process, the bubbles can also absorb and capture inclusions in the molten aluminum, thereby enhancing the slag removal ability of the refining agent.

[0022] SrSO 4 The Sr element generated by the reaction with the aluminum liquid enters the aluminum liquid, which can refine the modified eutectic Si phase and improve the strength and plasticity of the cast aluminum alloy. 2 During the floating process, the bubbles can also absorb and capture inclusions in the molten aluminum, thereby enhancing the slag removal ability of the refining agent.

[0023] KPO 3 The P element generated by reacting with aluminum liquid enters the aluminum liquid, which can refine the modified primary Si phase, not only improving the strength and plasticity of the cast aluminum alloy, but also enhancing the wear resistance of the cast aluminum alloy.

[0024] Na 2 B 4 O 7 By reacting with molten aluminum to generate element B which enters the molten aluminum, the coarse Fe-rich phase can be refined and modified, eliminating the harm of the coarse Fe-rich phase to the strength and plasticity of the cast aluminum alloy, thereby improving the strength and plasticity of the cast aluminum alloy.

[0025] Preferably, the method for preparing the refining agent in step 1 comprises the following steps in sequence:

[0026] Step 1: According to the composition and mass percentage of the refining agent, select NaCl, NaF, TiCl with a purity of ≥ 99.8% 3 、SrSO 4 , KPO 3 、Na 2 B 4 O 7 batching of raw materials;

[0027] Step 2: Add the ingredients into water at a temperature of 70°C and stir to dissolve into an aqueous solution, the mass ratio of water to ingredients being 1.2, and then heat to 100°C to evaporate the aqueous solution to obtain a solid crystal;

[0028] Step 3: crush the solid crystals into powder with a particle size of less than 2 mm, dry and dehydrate the powder at 160° C. for 4 hours to obtain the refining agent.

[0029] The deslagging effect of the refining agent is closely related to its preparation method. The conventional preparation method of the existing refining agent is to mechanically crush the chloride salt and the fluoride salt and then directly mix them to obtain the refining agent. The refining agent prepared by this method has independent components, resulting in a high melting point of the refining agent and low deslagging efficiency. The present invention breaks through the tradition and adopts a solution evaporation method to prepare the refining agent. Through solution evaporation, the components are re-solidified and recrystallized to form a eutectic with a lower melting point. For example, the melting point of NaCl is usually 801°C, and the melting point of NaF is usually 993°C. When the two form a NaCl·NaF eutectic, the melting point drops to 698°C, thereby greatly reducing the melting point of the refining agent, making the refining agent easier to dissolve in the cast aluminum alloy liquid, and enhancing the deslagging effect of the refining agent.

[0030] Preferably, the amount of the mixed gas in step 2 is 2-3 cubic meters per ton of cast aluminum alloy liquid, and the pressure of the mixed gas is (0.3-0.5)×10 5 Pa, the temperature of the casting aluminum alloy liquid during spray refining is 700-720°C, the spray refining time is 10-20 minutes, and the standing time of the casting aluminum alloy liquid is 20-30 minutes.

[0031] After refining by refining agent spraying, the slag content of the casting aluminum alloy liquid has been greatly reduced, but the casting aluminum alloy liquid still contains hydrogen. Although refining agent spraying refining also has the effect of removing hydrogen, the effect of removing hydrogen is limited. The reason is that the refining agent inevitably contains water. When spraying refining removes hydrogen, it will also bring in water, causing the casting aluminum alloy liquid to absorb hydrogen again, so that the dehydrogenation of refining agent spraying refining is always in a dynamic equilibrium process. Usually, it is difficult to reduce the hydrogen content of the casting aluminum alloy liquid to below 0.2ml / 100gAl by refining agent spraying refining. Therefore, in order to obtain highly clean casting aluminum alloy liquid, gas refining and dehydrogenation must also be carried out.

[0032] The mixed gas blowing refining adopts a metal pipe or a degasser to blow the mixed gas into the casting aluminum alloy liquid, so that the mixed gas forms fine bubbles and fully contacts and reacts with the casting aluminum alloy liquid, and hydrogen in the casting aluminum alloy liquid is brought out of the liquid surface during the floating process of the bubbles, thereby achieving the purpose of dehydrogenation.

[0033] The dehydrogenation effect of mixed gas spray refining is related to process parameters such as the amount of mixed gas, the temperature of the cast aluminum alloy liquid and the spray refining time. The greater the amount of mixed gas used and the longer the spray refining time, the better the dehydrogenation effect of the spray refining, but the production cost will increase accordingly. However, if the temperature of the cast aluminum alloy liquid is too high or the spray refining time is too long, the oxidation and burning of the aluminum alloy liquid will also increase. Preferably, the amount of mixed gas used is 2-3 cubic meters / ton of cast aluminum alloy liquid, and the pressure of the mixed gas is (0.3-0.5)×10 5Pa, the temperature of the casting aluminum alloy liquid during the spray refining is 700-720℃, and the spray refining time is 10-20 minutes. After the spray refining is completed and the scum on the surface of the casting aluminum alloy liquid is scraped off, a covering agent should be sprinkled on the surface of the casting aluminum alloy liquid in time to avoid oxidation, burning and hydrogen absorption of the casting aluminum alloy liquid.

[0034] Preferably, the mixed gas in step 2 is a mixed gas consisting of argon gas with a purity of ≥99.99%, sulfur hexafluoride and carbon monoxide, wherein the volume percentage of sulfur hexafluoride in the mixed gas is 9-11%, and the volume percentage of carbon monoxide is 3-5%.

[0035] In the existing gas injection refining technology, inert gas nitrogen or argon, or a mixture of inert gas and chlorine, is usually injected into the cast aluminum alloy liquid. Since nitrogen, argon and chlorine have small relative molecular weights and low gas densities, the relative molecular mass of nitrogen is 28.01 and the density is 1.25 kg / m 3 The relative molecular mass of argon is 39.94 and the density is 1.78 kg / m 3 The relative molecular mass of chlorine is 70.91 and the density is 3.21kg / m 3 This causes the bubbles to float faster in the cast aluminum alloy liquid, and the contact time between the bubbles and the cast aluminum alloy liquid is shorter, which greatly affects the dehydrogenation effect of gas injection refining. In addition, although the relative density of chlorine is relatively large, chlorine is a toxic gas with a strong pungent odor, which will not only seriously corrode the smelting furnace and smelting tools, but also cause serious environmental pollution.

[0036] Aiming at the problems and shortcomings of the existing gas injection refining technology, in order to improve the dehydrogenation effect of gas injection refining, the present invention injects a mixed gas consisting of argon with a purity of ≥99.99%, sulfur hexafluoride with a purity of ≥99.99% and carbon monoxide with a purity of ≥99.99% into the casting aluminum alloy liquid, wherein sulfur hexafluoride is a high-density, high-stability gas, and sulfur hexafluoride is non-toxic, non-combustible and non-corrosive. The relative molecular mass of sulfur hexafluoride is 146.05 and the density is 6.5kg / m 3, adding 9-11% by volume of sulfur hexafluoride to the mixed gas can significantly slow down the floating speed of bubbles in the casting aluminum alloy liquid, increase the contact time between the bubbles and the casting aluminum alloy liquid, and enable the bubbles to capture and absorb more hydrogen, thereby improving the dehydrogenation effect of gas injection refining. Adding 3-5% by volume of carbon monoxide to the mixed gas is to allow carbon monoxide to capture oxygen in the casting aluminum alloy liquid to form carbon dioxide, prevent oxygen from forming an aluminum oxide film on the surface of the bubble again with aluminum, enhance the ability of the bubbles to capture and absorb hydrogen, and improve the dehydrogenation effect of gas injection refining. Through mixed gas injection refining, the hydrogen content of the casting aluminum alloy liquid can usually be reduced to below 0.15ml / 100gAl, greatly improving the cleanliness of the casting aluminum alloy liquid.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention can significantly reduce the gas slag content of the cast aluminum alloy liquid, reduce the hydrogen content of the cast aluminum alloy liquid to below 0.15ml / 100gAl, and reduce the inclusion content to 0.1mm 2 / kgAl or less, which greatly improves the cleanliness of the cast aluminum alloy liquid, thereby improving the strength and plasticity of the cast aluminum alloy and solving the problem of mutual restriction between strength and plasticity. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] The refining and purification method of ZL101 cast aluminum alloy liquid comprises the following steps in sequence:

[0042] Step 1: using argon gas with a purity of 99.99% and a solid powder refining agent of 0.15% by weight of the cast aluminum alloy liquid to spray and refine the cast aluminum alloy liquid at 710° C. for 20 minutes to remove slag, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 35 minutes;

[0043] Step 2: Use a mixed gas consisting of argon gas, sulfur hexafluoride and carbon monoxide with a purity of 99.99% to spray and refine the 710°C cast aluminum alloy liquid for 15 minutes to remove hydrogen, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 25 minutes to obtain a highly clean cast aluminum alloy liquid. The amount of the mixed gas is 2.5 cubic meters / ton of cast aluminum alloy liquid, and the pressure of the mixed gas is 0.4×10 5Pa, the volume percentage of sulfur hexafluoride in the mixed gas is 10%, and the volume percentage of carbon monoxide is 4%.

[0044] Embodiment 2:

[0045] The refining and purification method of ZL203 cast aluminum alloy liquid comprises the following steps in sequence:

[0046] Step 1: using argon gas with a purity of 99.99% and a solid powder refining agent of 0.2% by weight of the cast aluminum alloy liquid to spray and refine the cast aluminum alloy liquid at 700°C for 25 minutes to remove slag, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 40 minutes;

[0047] Step 2: Use a mixed gas consisting of argon gas, sulfur hexafluoride and carbon monoxide with a purity of 99.99% to spray and refine the 720°C cast aluminum alloy liquid for 10 minutes to remove hydrogen, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 20 minutes to obtain a highly clean cast aluminum alloy liquid. The amount of the mixed gas is 2 cubic meters / ton of cast aluminum alloy liquid, and the pressure of the mixed gas is 0.5×10 5 Pa, the volume percentage of sulfur hexafluoride in the mixed gas is 11%, and the volume percentage of carbon monoxide is 5%.

[0048] Embodiment 3:

[0049] The refining and purification method of ZL305 cast aluminum alloy liquid comprises the following steps in sequence:

[0050] Step 1: Use argon gas with a purity of 99.99% and a solid powder refining agent of 0.1% by weight of the cast aluminum alloy liquid to spray and refine the cast aluminum alloy liquid at 720° C. for 15 minutes to remove slag, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 30 minutes;

[0051] Step 2: Use a mixed gas consisting of argon gas, sulfur hexafluoride and carbon monoxide with a purity of 99.99% to spray and refine the 700°C cast aluminum alloy liquid for 20 minutes to remove hydrogen, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for 30 minutes to obtain a highly clean cast aluminum alloy liquid. The amount of the mixed gas is 3 cubic meters / ton of cast aluminum alloy liquid, and the pressure of the mixed gas is 0.3×10 5 Pa, the volume percentage of sulfur hexafluoride in the mixed gas is 9%, and the volume percentage of carbon monoxide is 3%.

[0052] Embodiment 4:

[0053] The refining agent in step 1 of Example 1-3 of the present invention is composed of the following components in percentage by mass: NaCl 35.12%, NaF 19.84%, TiCl 316.51%, SrSO 4 10.06%, KPO 3 11.45%, Na 2 B 4 O 7 7.02%, the preparation method of the refining agent comprises the following steps in sequence: Step 1: According to the composition and mass percentage of the refining agent, NaCl, NaF, and TiCl with a purity of 99.8% are selected. 3 、SrSO 4 , KPO 3 、Na 2 B 4 O 7 The raw materials are prepared; step 2: adding the prepared ingredients into water at a temperature of 70°C, stirring and dissolving the prepared ingredients into an aqueous solution, wherein the mass ratio of water to the prepared ingredients is 1.2, and then heating the aqueous solution to 100°C to evaporate the aqueous solution to obtain solid crystals; step 3: crushing the solid crystals into powders with a particle size of less than 2 mm, and drying and dehydrating the powders at 160°C for 4 hours to obtain the refining agent.

[0054] Comparative Example 1:

[0055] The grade, refining and purification method steps and the composition of the refining agent used in step 1 of the cast aluminum alloy in this comparative example are the same as those in Example 1, except that evaporation recrystallization is not performed in the preparation method of the refining agent used. The specific steps are as follows: Step 1: According to the composition and mass percentage of the refining agent, NaCl, NaF, and TiCl with a purity of 99.8% are selected. 3 、SrSO 4 , KPO 3 、Na 2 B 4 O 7 The raw materials are batched; step 2: crushing the ingredients into powder with a particle size of less than 2 mm, drying and dehydrating the powder at 160° C. for 4 hours to obtain the refining agent.

[0056] Comparative Example 2:

[0057] The grade, refining and purification method and steps of the cast aluminum alloy in this comparative example are the same as those in Example 1, except that the refining agent used is a conventional refining agent available on the market, and the refining agent is composed of the following components in mass percentage: NaCl 36.13%, KCl 15.42%, CaF 2 16.84%, NaF 19.24%, C 2 Cl 6 12.37%, the refining agent is obtained by directly crushing and mixing the raw materials after drying and dehydration.

[0058] Comparative Example 3:

[0059] The grade, refining and purification method steps of the cast aluminum alloy in this comparative example are the same as those in Example 1, except that the mixed gas in step 2 is composed of argon gas with a purity of 99.99% and sulfur hexafluoride, and the volume percentage of sulfur hexafluoride in the mixed gas is 10%.

[0060] Comparative Example 4:

[0061] The grade, refining and purification method steps of the cast aluminum alloy in this comparative example are the same as those in Example 1, except that the mixed gas in step 2 is composed of argon gas with a purity of 99.99% and carbon monoxide, and the volume percentage of carbon monoxide in the mixed gas is 4%.

[0062] Comparative Example 5:

[0063] The grade, refining and purification method steps of the cast aluminum alloy in this comparative example are the same as those in Example 1, except that in step 2, argon gas with a purity of 99.99% is not sprayed into the cast aluminum alloy liquid.

[0064] Verification Example 1:

[0065] The melting points of the refining agents of Example 4, Comparative Example 1 and Comparative Example 2 were respectively detected by differential scanning calorimeter, and the results are shown in Table 1. As can be seen from Table 1, the melting point of the refining agent of Example 1 is significantly lower than the melting points of the refining agents of Comparative Example 1 and Comparative Example 2, indicating that the refining agent of the present invention has a lower melting point and is more easily dissolved in the casting aluminum alloy liquid, which is conducive to exerting the slag removal function of the refining agent and improving the slag removal efficiency. It is also conducive to reducing the refining temperature of the casting aluminum alloy liquid and reducing the oxidation and burning loss of the aluminum liquid.

[0066] Table 1 Melting point of refining agent

[0067] Example 4 Comparative Example 1 Comparative Example 2 Melting point / ℃ 723 1280 1014

[0068] Verification Example 2:

[0069] The hydrogen content and slag content of the cast aluminum alloy liquid after refining, degassing and deslagging of Examples 1-3 and Comparative Examples 1-5 were tested on site using a hydrogen meter and a slag meter. The results are shown in Table 2. As can be seen from Table 2, the hydrogen content of the cast aluminum alloy liquid in Examples 1-3 is less than 0.15 ml / 100 gAl, and the slag content is less than 0.1 mm 2 / kgAl. Since the refining agent used in Comparative Example 1 did not undergo evaporation recrystallization, and since the refining agent used in Comparative Example 2 was a conventional refining agent available on the market, the gas slag content of the cast aluminum alloy liquid was relatively high. Since the mixed gas used in Comparative Example 3 did not contain carbon monoxide, the mixed gas used in Comparative Example 4 did not contain sulfur hexafluoride, and the mixed gas used in Comparative Example 5 did not contain either carbon monoxide or sulfur hexafluoride, the gas slag content of the cast aluminum alloy liquid was also relatively high. By comparison, it can be seen that the present invention can significantly reduce the gas slag content of the cast aluminum alloy liquid and improve the cleanliness of the cast aluminum alloy liquid.

[0070] Table 2 Hydrogen content and slag content of cast aluminum alloy liquid

[0071] Hydrogen content / (ml / 100gAl) <![CDATA[Sludge content / (mm 2 / kg Al)]]> Example 1 0.122 0.068 Example 2 0.143 0.087 Example 3 0.124 0.079 Comparative Example 1 0.186 0.135 Comparative Example 2 0.242 0.187 Comparative Example 3 0.175 0.143 Comparative Example 4 0.189 0.122 Comparative Example 5 0.213 0.175

[0072] Verification Example 3:

[0073] The ZL101 cast aluminum alloy liquid after refining, degassing and deslagging of Example 1 and Comparative Examples 1-5 was cast into aluminum alloy ingots, and then samples were taken to test the tensile strength and elongation after fracture of the ZL101 cast aluminum alloy ingots. The results are shown in Table 3. It can be seen from Table 3 that the tensile strength of the cast aluminum alloy ingot using Example 1 is 265.41MPa, and the elongation after fracture is 8.71%. The tensile strength of the cast aluminum alloy ingots of Comparative Examples 1-5 is ≤245.65MPa, and the elongation after fracture is ≤6.54%. By comparison, it can be seen that by improving the cleanliness of the cast aluminum alloy liquid through the technical solution of the present invention, the strength and plasticity of the cast aluminum alloy can be greatly improved, and the contradiction between the strength and plasticity of the cast aluminum alloy is solved.

[0074] Table 3 Tensile strength and elongation after fracture of ZL101 cast aluminum alloy ingot

[0075]

[0076]

Claims

1. A method for refining and purifying cast aluminum alloy liquid, characterized in that: The following steps are included in sequence: Step 1: Use inert gas and solid powder refining agent to spray and refine the cast aluminum alloy liquid to remove slag, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for a period of time; Step 2: Use mixed gas to spray, refine and remove hydrogen from the cast aluminum alloy liquid, scrape off the scum on the surface of the cast aluminum alloy liquid, and then let the cast aluminum alloy liquid stand for a period of time to obtain a highly clean cast aluminum alloy liquid.

2. The refining and purification method of cast aluminum alloy liquid according to claim 1, characterized in that: The inert gas in step 1 is argon with a purity of ≥99.99%.

3. The refining and purification method of cast aluminum alloy liquid according to claim 1, characterized in that: The amount of the refining agent in step 1 is 0.1-0.2% of the weight of the cast aluminum alloy liquid.

4. The method for refining and purifying cast aluminum alloy liquid according to claim 1, characterized in that: In step 1, the temperature of the casting aluminum alloy liquid during the spray refining is 700-720° C., the spray refining time is 15-25 minutes, and the standing time of the casting aluminum alloy liquid is 30-40 minutes.

5. The refining and purification method of cast aluminum alloy liquid according to claim 1, characterized in that: The refining agent in step 1 is composed of the following components in mass percentage: NaCl 35.12%, NaF 19.84%, TiCl 3 16.51%, SrSO 4 10.06%, KPO 3 11.45%, and Na 2 B 4 O 7 7.02%.

6. The method for refining and purifying cast aluminum alloy liquid according to claim 1 or 5, characterized in that: The preparation method of the refining agent comprises the following steps in sequence: Step 1: According to the composition and mass percentage of the refining agent, NaCl, NaF, TiCl3, SrSO4, KPO3, and Na2B4O7 with a purity of ≥99.8% are selected as raw materials for batching; Step 2: Add the ingredients into water at a temperature of 70°C and stir to dissolve into an aqueous solution, the mass ratio of water to ingredients being 1.2, and then heat to 100°C to evaporate the aqueous solution to obtain a solid crystal; Step 3: crush the solid crystals into powder with a particle size of less than 2 mm, dry and dehydrate the powder at 160° C. for 4 hours to obtain the refining agent.

7. The method for refining and purifying cast aluminum alloy liquid according to claim 1, characterized in that: The amount of the mixed gas in step 2 is 2-3 cubic meters per ton of cast aluminum alloy liquid, and the pressure of the mixed gas is (0.3-0.5)×10 5 Pa.

8. The method for refining and purifying cast aluminum alloy liquid according to claim 1, characterized in that: During the spray refining in step 2, the temperature of the casting aluminum alloy liquid is 700-720° C., the spray refining time is 10-20 minutes, and the standing time of the casting aluminum alloy liquid is 20-30 minutes.

9. The method for refining and purifying cast aluminum alloy liquid according to claim 1 or 7, characterized in that: The mixed gas is a mixed gas composed of argon, sulfur hexafluoride and carbon monoxide, wherein the volume percentage of sulfur hexafluoride in the mixed gas is 9-11%, and the volume percentage of carbon monoxide is 3-5%.

10. The method for refining and purifying cast aluminum alloy liquid according to claim 1 or 7, characterized in that: The purity of argon, sulfur hexafluoride and carbon monoxide in the mixed gas is ≥99.99%.

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