Preparation method and application of refining modifier for iron-rich phase of regenerated aluminum alloy

Abstract

The invention provides a preparation method and application of a refinement modifier for an iron-rich phase of a secondary aluminum alloy, and the refinement modifier comprises the following components in percentage by mass: 60-75% of a fluxing agent, 15-30% of a boron-containing reagent and 9-11% of Co powder; wherein the fluxing agent is NaCl and KCl, and the mass fraction of the NaCl is 45.0 to 45.5 percent; and the boron-containing reagent is B2O3 or Na2B4O7. The B element in the [B] agent has a refinement effect on alpha-Al dendritic crystals in the waste aluminum melt, and the performance of the regenerated cast aluminum alloy is improved from the perspective of grain refinement. The [B] agent and Co powder jointly act to promote formation of primary alpha-Fe, finally atoms in an iron-rich eutectic phase are dissolved and transferred by combining a heat treatment means, the purpose of refining and modifying a harmful iron-rich phase is achieved, and the problems that in an existing low-iron-content aluminum alloy liquid, the iron removal cost is high, the refining and modifying effect of the iron-rich phase is poor, and a needle-sheet-shaped beta-Fe phase is left are solved. The preparation process is simple, raw materials are easy to obtain, cost is low, environment friendliness is achieved, operation is easy when the iron-rich phase is applied to the regenerated casting aluminum-silicon alloy, and the iron-rich phase refining modification efficiency is excellent.

Description

Technical Field

[0001] The invention relates to the field of alloy material recycling, and in particular to a preparation method and application of a refining modifier for a recycled aluminum alloy iron-rich phase. Background Art

[0002] As aluminum alloys are recycled, iron accumulates in the alloy, forming a coarse, hard and brittle iron-rich phase, which impairs the mechanical properties of the alloy, and Fe cannot be removed from the melt by standard operations. Therefore, recycled aluminum alloys can only be used in parts with low strength requirements, which greatly limits the application of recycled aluminum alloys.

[0003] Therefore, in actual production, there are two main methods to reduce the adverse effects of the iron-rich phase in aluminum alloys. One is to directly reduce the iron content in the aluminum alloy melt by gravity sedimentation, electromagnetic separation, centrifugal iron removal, etc.; the other is to change the morphology of the iron-rich phase in the alloy by adding alloying elements or performing specific heat treatment on the melt. Summary of the invention

[0004] The main purpose of the present invention is to provide a preparation method and application of a refining modifier for the iron-rich phase of a recycled aluminum alloy, aiming to solve the problems of low utilization rate of scrap aluminum, lack of deep iron removal technology, high cost, poor iron phase modification effect, and uneven quality of recycled aluminum products in the actual production process of existing recycled aluminum alloys.

[0005] To achieve the above object, the present invention provides a refining modifier for the iron-rich phase of a recycled aluminum alloy, which comprises, by mass fraction, 60% to 75% of a flux, 15% to 30% of a boron-containing reagent (for ease of description, some of the boron-containing reagents are referred to as [B] agents below) and 9% to 11% of Co powder;

[0006] Wherein, the flux is NaCl and KCl, in which the mass fraction of NaCl is 45.0-45.5%; the [B] agent is B 2 O 3 Or Na 2 B 4 O 7 .

[0007] According to an embodiment of the present application, the agent [B] is B 2 O 3 The content of is 24.5-28.0%; the content of flux is 62.05-65.75%; the content of Co powder is 9.75-9.95%.

[0008] According to the embodiment of the present application, the agent [B] is Na 2 B 4 O 7 , Na2 B 4 O 7 The content is 17.5-19.5%; the content of flux is 69.75-71.95%; the content of Co powder is 10.55-10.75%.

[0009] The present invention also provides a method for preparing a refining modifier for the iron-rich phase of a recycled aluminum alloy, comprising the following steps:

[0010] [B] agent and flux are dried and then ground evenly to obtain a mixed powder; Co powder and the mixed powder are mixed and pressed into tablets to obtain the refined modifier;

[0011] According to an embodiment of the present application, in the drying step, the drying temperature is 200-250° C., and the drying time is 2-3 hours; the rotation speed of the grinding equipment is 100-150 rpm, and the grinding time is 3-4 hours.

[0012] According to an embodiment of the present application, the modifier is compressed into tablets and then stored in a vacuum state; wherein the vacuum rate is 2.0 L / s and the power is 1.0 to 1.5 KW.

[0013] The present invention further provides an application of a refining modifier of an iron-rich phase of a recycled aluminum alloy in the preparation of a cast aluminum-silicon alloy melt from recycled waste aluminum, comprising:

[0014] The waste aluminum is disassembled, sorted, pretreated, batched, preheated, the temperature is increased, a flux is added, and the refining and modifying agent is added to perform an iron-rich phase refining and modifying treatment to obtain a casting aluminum-silicon alloy melt;

[0015] The step of batching comprises: adjusting the total iron content of the target cast aluminum-silicon alloy to be 0.0-0.5%;

[0016] The flux contains NaCl and KCl, wherein the mass fraction of NaCl is 45.0-45.5%, the mass fraction of KCl is 54.5-55.0%, and the amount of the flux added is 0.65-0.70wt% of the mass of the scrap aluminum;

[0017] The amount of the refinement modifier added is 1.8 to 2.5% of the mass of the scrap aluminum. 2 O 3 When the refining and modifying agent is 2.0-2.5% of the mass of the scrap aluminum; when [B] agent is Na 2 B 4 O 7 When the amount of the reformer is 1.8 to 2.3% times the mass of the scrap aluminum.

[0018] The lifting temperature is 740-770°C;

[0019] The preheating temperature of the preheating step is 250-350° C., and the preheating time is 1-2 hours.

[0020] The modifier is pressed to the bottom of the aluminum alloy smelting furnace to perform iron-rich phase refinement and modification treatment.

[0021] The present invention also provides a method for preparing a cast aluminum-silicon alloy, comprising:

[0022] The cast aluminum-silicon alloy melt is subjected to component detection, component blending, refining, slag removal, heat preservation, casting and heat treatment;

[0023] The composition detection analyzes the content of Al, Si, Mg and Fe elements in the melt.

[0024] According to the implementation mode of the present application, the heat treatment is divided into solution treatment and aging stages; wherein, in the solution treatment stage, the cast recycled aluminum product is heated at 500-540°C for 4-6 hours, and then immediately immersed in water for rapid cooling; in the aging stage, the rapidly cooled recycled aluminum product is heated at 160-190°C for 5-8 hours and then taken out for rapid cooling.

[0025] The refining and modifying agent for the iron-rich phase of the recycled aluminum alloy provided by the present invention, the boride provided by the [B] agent can effectively inhibit the formation of the needle-like β-Fe phase; the addition of the B element can promote the precipitation of slag-forming elements in large quantities at the grain boundaries, so that Al, Si, and Fe are combined into compounds to form a primary α-Fe phase. The Co element, as a neutralizing element for modifying the iron-rich phase of the aluminum alloy, has the functions of spheroidizing the iron-rich phase, fixing the recycled aluminum alloy matrix, and strengthening the alloy during the heat treatment process. The [B] agent and Co powder are used as effective refining and modifying components to achieve the purpose of refining iron. The refining and modifying agent can further crush, refine, and spheroidize the α-Fe phase during the heat treatment process, effectively solving the problem that the aluminum alloy matrix is ​​split due to the presence of a large amount of needle-like β-iron phase, fine cracks are generated, and product performance is affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 The SEM images of typical iron-rich phases in the recycled cast aluminum alloy of the present invention; (a) is magnified 7000 times; (b) is magnified 10000 times;

[0028] Figure 2is a stress-strain comparison curve diagram of the recycled cast aluminum alloy of the present invention;

[0029] Figure 3 It is a stress-strain comparison curve diagram of the recycled cast aluminum alloy of Example 1, Comparative Example 1 and Comparative Example 3 of the present invention;

[0030] Figure 4 The SEM image and EDS image of the typical iron-rich phase of the recycled cast aluminum alloy without solution aging treatment of the present invention; wherein (a) is magnified 7000 times; (b) is magnified 6500 times;

[0031] Figure 5 The SEM image and EDS image of the regenerated cast aluminum alloy after solution aging treatment of the present invention; wherein (a) and (b) are images of Example and Example 2 magnified 1000 times, respectively;

[0032] Figure 6 The SEM images of typical iron-rich phases in the recycled cast aluminum alloys of Example 1, Example 2, Comparative Example 1 and Comparative Example 3 of the present invention are shown; wherein (a) and (b) are images of Comparative Example 1 magnified 10,000 times and 4,000 times, respectively; (c) and (d) are images of Comparative Example 3 magnified 8,000 times and 3,000 times, respectively; (e) and (f) are images of Example 1 magnified 5,000 times and 8,000 times, respectively; (g) and (h) are images of Example 2 magnified 8,000 times and 5,000 times;

[0033] Figure 7 This is a SEM image of a typical iron-rich phase of the recycled cast aluminum alloy of Comparative Example 4 of the present invention, magnified 7000 times;

[0034] Figure 8 This is a SEM image of the recycled cast aluminum alloy of Comparative Example 5 of the present invention magnified 2000 times;

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0037] It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments rather than to limit the scope of protection of the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used in the present invention are consistent with the prior art mastery of those skilled in the art and the description of the present invention, and any prior art methods, equipment and materials similar to or equivalent to the methods, equipment and materials in the embodiments of the present invention may also be used to implement the present invention. It should be known to those skilled in the art that, as an explanation of the present application document, "Stress" can be expressed as stress and "Strain" can be expressed as strain without affecting the actual understanding of the technical solution of the present application.

[0039] When the embodiments give numerical ranges, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. The test methods in the following embodiments without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The materials or reagents required in the following embodiments are commercially available unless otherwise specified.

[0040] The present invention provides a refining modifier for the iron-rich phase of a recycled aluminum alloy, which comprises, by mass fraction, 60% to 75% of a flux, 15% to 30% of a boron-containing reagent (for ease of description, some of the boron-containing reagents are referred to as [B] agents in the following text) and 9% to 11% of Co powder; if the refining modifier contains any one of the [B] agent, the flux and the Co powder, it is called a refining modifier for the iron-rich phase of a recycled aluminum alloy;

[0041] The flux is NaCl and KCl, and its addition helps to solve the high viscosity and agglomeration problems caused by agent [B], and can increase the contact opportunity between agent [B] and the melt. In the flux, the mass fraction of NaCl is 45.0-45.5% (preferably 45.0%); the agent [B] is B 2 O 3 Or Na 2 B 4 O 7 . Because the unit mass B 2 O 3 and Na 2 B 4 O 7 The B element content varies, and the [B] agent can be selected according to the actual situation:

[0042] Exemplarily, the [B] agent is B 2 O 3 When B 2 O 3The content is 24.5-28.0% (preferably 24.63%); the content of flux is 62.05-65.75% (preferably 65.52%); the content of Co powder is 9.75-9.95% (preferably 9.85%).

[0043] Exemplarily, the [B] agent is Na 2 B 4 O 7 When, Na 2 B 4 O 7 The content is 17.5-19.5% (preferably 18.62%); the content of flux is 69.75-71.95% (preferably 70.74%); the content of Co powder is 10.55-10.75% (preferably 10.64%).

[0044] The ingredients within the above numerical range can ensure the expected iron-rich phase refinement and modification effect while saving raw material costs as much as possible and reducing the negative impact of [B] agent and Co powder on the aluminum alloy melt.

[0045] Excessive [B] agent is easily converted into a highly viscous liquid under high temperature conditions and floats on the surface of the aluminum melt or adheres to the inner wall of the molten aluminum, limiting the surface area of ​​the [B] agent in contact with the melt, affecting the fluidity of the melt, and restricting the exchange of elements in the melt; excessive Co element not only causes waste, but also introduces new impurities Co and has a negative impact on the quality of recycled aluminum products.

[0046] The boride provided by the [B] agent can be adsorbed on the surface of the iron-rich phase, changing the dominant growth orientation of the iron-rich phase at the initial stage of the formation of the iron-rich phase, and effectively inhibiting the formation of the needle-like β-Fe phase; secondly, from the perspective of slag formation, the primary α-Fe phase is also called the slag phase. The addition of the B element in the [B] agent can increase the chemical activity coefficient f of slag-forming elements such as Si, Fe, and Co. Since the activity of these slag-forming elements in Al is constant, the solubility of the slag-forming elements in the melt is reduced, and the slag-forming elements are promoted to precipitate in large quantities at the grain boundaries, so that Al, Si, Fe, and Fe are combined into compounds to form the primary α-Fe phase; the excess B element can react with the melt during the smelting process to form aluminum-boron compounds (AlB x ), which can serve as the core of heterogeneous nucleation of aluminum grains, so it has a certain refinement effect on the α-Al dendrites in the waste aluminum melt and can improve the performance of recycled cast aluminum alloy.

[0047] As a neutralizing element for the modification of the iron-rich phase of aluminum alloy, the Co element will combine with the iron-rich phase to form an iron-cobalt compound during the rapid cooling of the melt. This special iron-rich intermetallic compound has a strong tendency to dissolve and spheroidize during the subsequent heat treatment. After it is transformed into granular or spherical form, it has a certain degree of fixing effect on the matrix and hinders the dislocation of the elastic strain field, thereby strengthening the alloy.

[0048] Mainly through the combined action of [B] agent and Co powder, combined with the regulation of various elements and condition control, the refining and modifying effects are respectively played in the smelting section and heat treatment section of scrap aluminum recycling, and the iron-rich phase that cannot be separated by conventional aluminum alloy iron removal methods (such as dilution method, gravity sedimentation method, filtration method) is refined and modified to form spherical and granular iron-rich phases that do not affect or even improve the comprehensive mechanical properties of recycled aluminum alloy products.

[0049] The present invention also provides a method for preparing a refining modifier for the iron-rich phase of a recycled aluminum alloy, comprising the following steps:

[0050] [B] agent and flux are dried and then ground evenly to obtain a mixed powder; Co powder and the mixed powder are mixed and pressed into tablets to obtain the refined modifier;

[0051] For example, Co powder is easily oxidized to become ineffective, such as being oxidized to CoO, so the Co powder is stored in a vacuum environment, such as a vacuum glove box;

[0052] Exemplarily, when the flux is dried, such as by using an oven, the drying temperature is 110-130°C (preferably, the drying temperature is 110°C), and the drying time is 3-5 hours (preferably, the drying time is 5 hours), which can avoid the problem of weighing error caused by water absorption of chloride salt. In the step of drying the mixed powder, such as by using a resistance furnace for drying, the drying temperature is 200-250°C (preferably, the drying temperature is 200°C), and the drying time is 2-3 hours (preferably, the drying time is 2.5 hours), which can remove the crystal water in the raw material;

[0053] For example, if the grinding is performed using a ball mill, the speed of the ball mill is 100-150 rpm (preferably, the ball mill speed is 100 rpm), and the grinding time is 3-4 hours (preferably, the grinding time is 3 hours). Uniform grinding can increase the uniformity of the internal reaction of the melt during the addition of the refinement modifier, and further improve the efficiency of the refinement and modification of the iron-rich phase.

[0054] As another example, the modifier is compressed and stored in a vacuum state; for example, it is compressed by a 769YP-24B powder tablet press, or it is compressed by an external vacuum machine, the vacuum rate of which is 2.0 L / s and the power is 1 to 1.5 KW.

[0055] The present invention further provides an application of a refining modifier of an iron-rich phase of a recycled aluminum alloy in the preparation of a cast aluminum-silicon alloy melt from recycled waste aluminum, comprising:

[0056] The waste aluminum is disassembled, sorted, pretreated, batched, preheated, and the temperature is increased, and a flux and a refining and modifying agent are added to refine and modify the iron-rich phase to obtain a casting aluminum-silicon alloy melt;

[0057] Among them, the pretreatment steps include: paint removal, cleaning, crushing, packaging and drying.

[0058] For example, the ingredients are adjusted according to the target cast aluminum-silicon alloy so that the total iron content is 0.0-0.5%; the refining modifier can have a stabilizing effect. If the iron content of the raw material is >0.5%, the iron removal method such as dilution method, gravity sedimentation method, filtration method, etc. can be combined to remove part of the easily separated Fe phase at the front end of the process, and then the refining modifier is combined to spheroidize and modify the remaining harmful Fe phase that is difficult to separate.

[0059] Exemplarily, preheating is performed in a furnace, such as an aluminum alloy melting furnace, with a preheating temperature of 250 to 350° C. and a duration of 1 to 2 hours.

[0060] Exemplarily, the flux contains NaCl and KCl, wherein the mass fraction of NaCl is 45.0-45.5% (preferably 45.0%), the mass fraction of KCl is 54.5-55.0% (preferably 55.0%), and the amount of the flux added is 0.65-0.70wt% (preferably 0.67%) of the mass of the scrap aluminum;

[0061] The flux is weighed and put into the furnace, and the furnace temperature is raised to 740-770°C. After the temperature stabilizes, an appropriate amount of the modifier is pressed to the bottom of the furnace for refinement and modification of the iron-rich phase, and then left to stand for 40-60 minutes. In order to prevent the modifier from staying on the liquid surface with the slag due to the excessive surface tension of the liquid aluminum, it needs to be pressed to the bottom of the furnace. If a 316 stainless steel high-temperature resistant bell jar is used, the impurity Fe content will not increase due to tool melting.

[0062] For example, the amount of the refinement modifier added is 1.8-2.5% of the mass of the scrap aluminum; the mass of the refinement modifier material can be adjusted according to the mass of the scrap aluminum before tableting; if [B] agent is B 2 O 3 When the amount of the refinement and modification is 2.0-2.5% (preferably 2.03%) of the mass of the scrap aluminum; if [B] agent is Na 2 B 4 O 7 When the amount of the refined and modified aluminum is 1.8-2.3% (preferably 1.88%) of the mass of the scrap aluminum.

[0063] The present invention also provides a method for preparing a cast aluminum-silicon alloy, comprising:

[0064] The cast aluminum-silicon alloy melt is subjected to composition detection, composition blending, refining, slag removal, insulation, casting and heat treatment.

[0065] For example, the content of Al, Si, Mg and Fe elements in the component melt is analyzed by a CCD direct reading spectrometer.

[0066] Exemplarily, the component blending process includes adding Al-Si master alloy, Al-Mg master alloy, Al ingot, industrial grade magnesium flakes, etc. to supplement the components.

[0067] Exemplarily, the heat treatment is divided into solution treatment and aging stages; in the solution treatment stage, the quenched cast recycled aluminum product is placed in a solution treatment aging furnace at 500-540°C (preferably, 510°C) and heated for 4-6 hours (preferably, 6 hours), and then immediately immersed in room temperature water for quenching; in the aging stage, the quenched recycled aluminum product is placed in a solution treatment aging furnace at 160-190°C (preferably, 190°C) and heated for 5-8 hours (preferably, 8 hours), taken out and quenched to obtain a cast aluminum alloy.

[0068] Heat treatment can not only change the primary silicon and eutectic silicon in the aluminum-silicon alloy, but also has a significant impact on the final refinement and modification effect of the iron-rich phase. During the heat treatment process, the driving force for the atomic dissolution and transfer of the iron-rich cobalt intermetallic compounds makes the branches and top parts passivated and tend to rotate, further improving the sphericity of the iron-rich phase and gradually changing the morphology to a spherical shape.

[0069] For example, the refinement modifier is applied to prepare cast aluminum-silicon alloy. After the refinement modifier is added to aluminum liquid containing impurity iron, the B element in the [B] agent combines with other elements in the melt to transform into AlB x ,FeB x And other fine borides. AlB x In the melting process of aluminum-silicon alloy, it can be used as a core particle for heterogeneous nucleation of Al crystals that resists silicon poisoning, which is beneficial to refine the grains of recycled aluminum alloy and further improve the mechanical properties of recycled aluminum alloy products from the perspective of grain refinement. x In the early stage of the formation of the iron-rich phase, it can promote the transformation of iron-rich intermetallic compounds into finer and rounder α-Fe. After these iron-rich intermetallic compounds are combined with Co powder, they will be further broken, refined and spheroidized in the subsequent heat treatment process, effectively solving the problem of the aluminum alloy matrix being split due to the presence of a large amount of needle-like β-iron phase, causing fine cracks and affecting product performance.

[0070] For further understanding of the present invention, examples are given below:

[0071] The following examples and comparative examples all use scrap aluminum with an iron content of 0.35-0.45wt% as the raw material for recycled aluminum alloy, and cast aluminum-silicon aluminum alloy as the target recycled aluminum alloy. In order to ensure the rigor and scientificity of the following examples and comparative examples, the scrap aluminum in the following examples and comparative examples has been uniformly disassembled, sorted, pretreated, and melt composition prepared, and the key Fe, Mg, and Si elements are adjusted to the target chemical composition of the cast aluminum-silicon alloy, without the need to supplement additional elements in the subsequent iron-rich phase spheroidization modification process. Its chemical composition is shown in Table 1. The scrap aluminum after component preparation is a hard solid material, and its quality is difficult to control. Therefore, in the examples and comparative examples, the mass of other materials is adjusted accordingly according to their weighed mass according to a fixed percentage.

[0072] Table 1 Chemical composition of relevant aluminum alloys

[0073]

[0074] Example 1

[0075] Select [B] agent as B 2 O 3 Prepare the refining modifier of the iron-rich phase of the recycled aluminum alloy, weigh each component according to the required refining modifier dosage, among which B 2 O 3 The aluminum content of aluminum scrap is 24.63%, the Co powder is 9.85%, and the flux is 65.52%. The weighed mixed powder is placed in a resistance furnace at 200°C for drying for 2.5 hours; after drying, it is placed in a ball mill for ball milling for 3 hours, and the ball milling speed is 100rpm; the Co powder is taken out from the glove box, mixed with the mixed powder and ground together for 15 minutes; 3.589g of the refining modifier (2.03% of the mass of the waste aluminum) is weighed, and it is pressed into tablets by a powder tablet press. After pressing, an external vacuum machine is used to evacuate the air at a rate of 2.0L / s, and the vacuum is stored for standby use.

[0076] Weigh 176.81g of the waste aluminum after the composition adjustment, put it into the aluminum alloy melting furnace and preheat it at 250℃ for 1h; place NaCl and KCl in an oven at 110℃ and keep them warm and dry for 5h. Weigh 1.185g of flux and put it into the aluminum alloy melting furnace, and raise the temperature of the melting furnace to 750℃; after the temperature stabilizes, take out the vacuum-preserved pressed sheet, press it to the bottom of the melting furnace with a 316 stainless steel high-temperature resistant bell jar, take out the bell jar after reacting for 10min, close the furnace and keep it warm for 30min; use nitrogen to refine the regenerated aluminum melt, insert a graphite tube with a nitrogen flow rate of 4.5m / s into the melt, stir and refine for 20min, then let the melt stand for 10min and remove a small amount of scum on the surface; gently stir the remaining aluminum alloy liquid, and finally cast it into a graphite mold preheated to 80℃.

[0077] The quenched cast recycled aluminum product was placed in a constant temperature 510℃ solution aging furnace for 6 hours, and then immediately immersed in room temperature water for quenching; the quenched recycled aluminum product was placed in a constant temperature 190℃ solution aging furnace for 8 hours to obtain a recycled cast aluminum alloy, named Neutralizer B 2 O 3 -Co.

[0078] Example 2

[0079] The agent [B] is selected as Na 2 B 4 O 7 Prepare the refining modifier for the iron-rich phase of the recycled aluminum alloy, weigh each component according to the required refining modifier dosage, among which Na 2 B 4 O 7 The content of aluminum waste is 18.62%, the content of Co powder is 10.64%, and the content of flux is 70.74%. Except that the amount of refined and modified aluminum is changed to 3.325g (1.88% of the mass of waste aluminum), the other preparation conditions remain unchanged.

[0080] 176.85g of the waste aluminum after the composition adjustment was weighed as the raw material. Except for the change in the quality of the raw material, the other steps and conditions of the iron-rich phase modification and smelting process remained unchanged to obtain a recycled cast aluminum alloy named Neutralizer Na 2 B 4 O 7 -Co.

[0081] Example 3

[0082] Select [B] agent as B 2 O 3 Prepare the refining modifier of the iron-rich phase of the recycled aluminum alloy, weigh each component according to the required refining modifier dosage, among which B 2 O 3 The content of aluminum scrap is 28%, Co powder is 10.64%, and flux is 61.36%. Except that the amount of refined modification is changed to 3.535g (2.03% of the mass of waste aluminum), other preparation conditions remain unchanged.

[0083] 186.21g of the waste aluminum with the prepared components was weighed as the raw material and put into the aluminum alloy melting furnace for preheating at 250℃ for 1h; NaCl and KCl were placed in an oven at 110℃ for 5h. 1.25g of flux was weighed and put into the aluminum alloy melting furnace. The subsequent steps and conditions of the other iron-rich phase modification and smelting process were the same as those in Example 1, and the regenerated cast aluminum alloy was obtained, named Neutralizer 28B. 2 O 3 -Co.

[0084] Example 4

[0085] The agent [B] is selected as Na 2 B 4 O 7 Prepare the refining modifier for the iron-rich phase of the recycled aluminum alloy, weigh each component according to the required refining modifier dosage, among which Na 2 B 4 O 7 The content of aluminum waste is 19.5%, the content of Co powder is 10.64%, and the content of flux is 69.86%. Except that the amount of refined and modified aluminum is changed to 3.535g (1.88% of the mass of waste aluminum), the other preparation conditions remain unchanged.

[0086] 188.04g of the waste aluminum with the prepared components was weighed as the raw material and put into the aluminum alloy melting furnace for preheating at 250℃ for 1h; NaCl and KCl were placed in an oven at 110℃ for 5h. 1.26g of flux was weighed and put into the aluminum alloy melting furnace. The subsequent steps and conditions of the other iron-rich phase modification and smelting process were the same as those in Example 2 to obtain a recycled cast aluminum alloy named Neutralizer 19.5Na 2 B 4 O 7 -Co.

[0087] Comparative Example 1

[0088] 188.02g of scrap aluminum with component adjustment was weighed and put into an aluminum alloy melting furnace for preheating at 250℃ for 1h; then the temperature of the melting furnace was increased to 750℃; after the temperature stabilized, the furnace was closed and kept warm for 40min; nitrogen was used to refine the regenerated aluminum melt, and a graphite tube with a nitrogen flow rate of 4.5m / s was inserted into the melt for stirring and refining for 20min. After that, the melt was allowed to stand for 10min and a small amount of scum on the surface was removed; the remaining aluminum alloy liquid was slightly stirred and finally cast into a graphite mold preheated to 80℃.

[0089] The quenched cast recycled aluminum product is placed in a constant temperature 510℃ solution aging furnace for 6 hours, and then immediately immersed in room temperature water for quenching; the quenched recycled aluminum product is placed again in a constant temperature 190℃ solution aging furnace for 8 hours to obtain a recycled cast aluminum alloy, named Without Neutralizer.

[0090] Comparative Example 2

[0091] Select [B] agent as B 2 O 3 Preparation of recycled aluminum alloy iron-rich phase modifier, weigh 5g B 2 O 3Place it in a resistance furnace at 200°C and dry it for 2.5 hours; place the dried [B] agent in a ball mill and ball mill it for 3 hours at a speed of 100 rpm; weigh 0.9419 g of the ball-milled powder [B] agent and press it into tablets. After pressing the tablets, evacuate the modifier containing [B] agent and store it for later use.

[0092] 188.39 g of the aluminum scrap after the composition adjustment was weighed and put into the aluminum alloy melting furnace for preheating at 250°C for 1 hour; then the temperature of the melting furnace was raised to 750°C; after the temperature stabilized, the modifier containing [B] agent stored in vacuum was taken out, and the bell jar was pressed to the bottom of the melting furnace. After the reaction for 10 minutes, the bell jar was taken out, and the furnace was closed and kept warm for 30 minutes; the subsequent operations were the same as those in Comparative Example 1. Named Without Coand Flux.

[0093] Comparative Example 3

[0094] Select [B] agent as B 2 O 3 Preparation of iron-rich phase modifier for recycled aluminum alloy, according to B 2 O 3 The weighted powders containing agent [B] and flux are placed in a resistance furnace at 200°C for drying for 2.5 hours; after drying, they are placed in a ball mill for 3 hours at a ball mill speed of 100 rpm; 2.3357 g of the powders containing agent [B] and flux are weighed, ground and tableted, and after tableting, the modifier containing agent [B] and flux is evacuated and stored for later use.

[0095] Weigh 127.63g of the scrap aluminum after the composition adjustment, put it into the aluminum alloy melting furnace and preheat it at 250℃ for 1h; weigh 0.8551g of flux and put it into the aluminum alloy melting furnace, and raise the temperature of the melting furnace to 750℃; after the temperature stabilizes, take out the vacuum-preserved modifier containing [B] agent and flux, press it to the bottom of the melting furnace with a bell jar, react for 10min, take out the bell jar, close the furnace and keep it warm for 30min; the subsequent operations are the same as those in Comparative Example 1. Named Without Co.

[0096] Example 1-Example 2 are the refinement modifiers and fluxes of the iron-rich phase at the optimal content, wherein Example 1 uses agent [B] as B 2 O 3 In Example 2, agent [B] is Na 2 B 4 O 7 The difference between Example 3 and Example 1, and between Example 4 and Example 2 is that the contents of the components of the iron-rich phase refining modifier are different.

[0097] Comparative Example 2 and Comparative Example 3 are both iron-rich phase modifiers, but their components are different. Among them, Comparative Example 2 is a modifier containing agent [B], and Comparative Example 3 is a modifier containing agent [B] and flux.

[0098] 1. Comparative Example 3 Compared with Comparative Example 2, a flux component is added to the iron-rich phase modifier, and the fluidity of the scrap aluminum melt is significantly enhanced during the smelting process. Figure 1 From the typical morphology of the iron-rich phase in (b), it can be seen that, with the assistance of the flux, the [B] agent has the ability to promote the transformation of the iron-rich phase to the non-acicular α-Fe phase; Figure 1 (a) It can be seen that when the flux is lacking during the preparation and application of the flux, the effect of the modifier decreases.

[0099] After the recycled cast aluminum alloys of Comparative Examples 2 and 3 were processed into standard test bars, their tensile strength was tested on a universal mechanical testing machine to obtain the tensile strength performance parameters related to Table 2. The stress-strain comparison curves are shown in Table 2. Figure 2 shown.

[0100] Table 2 Tensile strength performance parameters of recycled cast aluminum alloys in Example 2 and Comparative Example 3

[0101]

[0102] Combined stress-strain curve Figure 2 As shown in Table 2, the tensile strength performance parameter analysis shows that the introduction of [B] agent significantly reduces the fluidity of the waste aluminum melt. Through the action of the low melting point and low viscosity flux component, the tensile strain of the recycled cast aluminum alloy is increased from 1.59-2.42% to 7.96-8.55%. In addition, it does not cause any negative impact on the tensile strength of the recycled cast aluminum alloy. Without Co, the tensile strength remains above 240MPa.

[0103] 2. The stress-strain comparison curves of the recycled cast aluminum-silicon alloys of Example 1, Comparative Example 1 and Comparative Example 3 are shown in FIG. Figure 3 shown.

[0104] Among them, stress-strain curves 1-3 correspond to Neutralizer B in Example 1 respectively. 2 O 3 -Co, i.e., a refining modifier containing an iron-rich phase was added; Comparative Example 3 Without Co, i.e., a modifier containing [B] agent and flux was added; Comparative Example 1 Without Neutralizer, i.e., no modifier was added.

[0105] Combining the tensile strength performance parameter table of the three as shown in Table 3, it can be seen that the addition of the modifier containing [B] agent and flux can effectively modify the iron-rich phase in the recycled cast aluminum alloy, thereby reducing its negative impact on the tensile strength. The tensile strength of Without Co is increased by 27.60MPa compared with Without Neutralizer; while Neutralizer B 2 O 3 -Co optimized the modifier components, and a refined modifier was obtained by adding Co powder to the components, which further improved the tensile strength of the recycled cast aluminum-silicon alloy to 269.17MPa.

[0106] Table 3 Tensile strength performance parameters of recycled cast aluminum alloys of Example 1, Comparative Examples 1 and 3

[0107]

[0108] 3. The effect of Co powder on iron-rich intermetallic compounds is mainly concentrated in the heat treatment process (including solution treatment and aging treatment).

[0109] Figure 4 and Figure 5 The cross-sectional microstructures of the regenerated cast aluminum-silicon alloys prepared in Example 1 and Example 2 before and after heat treatment are shown respectively. It can be seen that after adding the iron-rich phase refinement modifier, the [B] agent immediately plays a modifying role, but a small part of the iron-rich phase still presents an unfavorable needle-like shape (such as Figure 4 (b)); the energy spectrum scanning signals of the elements Co and Fe are highly overlapped, indicating that during the melting process, the Co element will fully enter the iron-rich phase and combine with it; after solution and aging treatment, the morphology of the iron-rich intermetallic compound has undergone extremely significant changes. The Co-containing iron-rich phase tends to be fine and round, and after spheroidization, the fine iron-rich phase is evenly distributed between the α-Al dendrites.

[0110] 4. The SEM images of typical iron-rich phases of the recycled cast aluminum alloys in Example 1, Example 2 and Comparative Example 1 and Comparative Example 3 are as follows: Figure 6 Among them, (a) (b) are SEM images of Comparative Example 1 Without Neutralizer; (c) (d) are SEM images of Comparative Example 3 Without Co; (e) (f) are SEM images of Example 1 Neutralizer B 2 O 3 -SEM images of Co; (g) (h) are SEM images of Neutralizer Na in Example 2 2 B 4 O 7 -SEM image of Co.

[0111] It can be seen that after being polished with 210#, 500#, 1000#, 2000#, and 4000# metallographic sandpaper and polished with metallographic polishing cloth, different sections of recycled casting alloys exposed iron-rich phases with obvious differences in size and morphology.

[0112] Among them, Figure 6 (a) (b) is the comparative example 1 without any modifier. The iron-rich phase is mostly needle-shaped β-Fe phase, and the size is mostly 10-20 μm. During the stretching process of the cast aluminum-silicon alloy, this kind of high-hardness and high-modulus coarse needle-shaped iron-rich phase easily causes stress concentration and forms a fracture source. The fracture source causes the alloy crack to expand during the stretching process, thereby reducing the mechanical properties ( Figure 3 Curve 3);

[0113] like Figure 6 (c)(d), after adding the modifier containing [B] agent and flux, the iron-rich phase in the melt did not show obvious spheroidization and refinement after heat treatment, but the needle-like β-Fe phase tended to transform into the skeletal α-Fe;

[0114] The iron-rich phase refinement modifier components of Example 1 and Example 2 include agent [B], flux and Co powder. 2 O 3 Or Na 2 B 4 O 7 When Figure 6 (e)(f) or (g)(h) show that after the action of [B] agent, the Chinese character-shaped and skeleton-shaped α-Fe phases and some residual needle-shaped β-Fe phases are combined with the Co element. Under the action of heat treatment, the typical iron-rich phase in the recycled cast aluminum-silicon alloy undergoes obvious spheroidization and refinement. The single iron-rich phase disintegrates into many fine particles. The refining and modification effect is the best, and the iron phase size is refined to about 1μm.

[0115] 5. Compared with Example 1, Example 3 2 O 3 The content of Na 2 B 4 O 7 The content of increased from 18.62% to 19.5%. Figure 7 and Figure 8 It can be seen that when the content of [B] agent is increased, the typical iron-rich phase in the recycled cast aluminum-silicon alloy is still refined and modified to a certain extent, and the skeletal α-Fe phase is transformed into fine spheres after the heat treatment process, but compared with Example 1-Example 2, the degree of spheroidization and dispersion is greatly reduced. Therefore, when the content of each component of the refining modifier is different, it has different modification effects; but when the content of each component is optimal, the degree of spheroidization and dispersion is better, and the refining and modification effect is the best.

[0116] In summary, the above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A refinement modifier for the iron-rich phase of a recycled aluminum alloy, characterized in that: In terms of mass fraction, the refining modifier includes 60% to 75% flux, 15% to 30% boron-containing reagent and 9% to 11% Co powder; Wherein, the flux is NaCl and KCl, in which the mass fraction of NaCl is 45.0-45.5%; and the boron-containing reagent is B2O3 or Na2B4O7.

2. The refining modifier for the iron-rich phase of the recycled aluminum alloy according to claim 1, characterized in that: The boron-containing reagent is B2O3, the content of B2O3 is 24.5-28.0%; the content of flux is 62.05-65.75%; and the content of Co powder is 9.75-9.95%.

3. The refining and modifying agent for the iron-rich phase of the recycled aluminum alloy according to claim 1, characterized in that: The boron-containing reagent is Na2B4O7, the content of Na2B4O7 is 17.5-19.5%; the content of flux is 69.75-71.95%; and the content of Co powder is 10.55-10.75%.

4. A method for preparing a refining modifier for the iron-rich phase of a recycled aluminum alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: The boron-containing reagent and the flux are dried and then ground evenly to obtain a mixed powder; the Co powder and the mixed powder are mixed and pressed into tablets to obtain the refined modifier.

5. The method for preparing the refining modifier of the iron-rich phase of the recycled aluminum alloy according to claim 4, characterized in that: In the drying step, the drying temperature is 200-250° C., and the drying time is 2-3 hours; the grinding speed is 100-150 rpm, and the grinding time is 3-4 hours.

6. The method for preparing the iron-rich phase refining and modifying agent for recycled aluminum alloy according to claim 4, characterized in that: The modifier is compressed into tablets and then stored in a vacuum state; wherein the vacuum rate is 2.0 L / s and the power is 1 to 1.5 KW.

7. Application of a regenerated aluminum alloy iron-rich phase refiner in the preparation of cast aluminum-silicon alloy melt from waste aluminum, characterized in that: include: The waste aluminum is disassembled, sorted, pretreated, batched, preheated, and the temperature is increased, and a flux and a refining and modifying agent as described in any one of claims 1 to 3 are added to perform an iron-rich phase refining and modifying treatment to obtain a casting aluminum-silicon alloy melt; The step of proportioning the ingredients includes: adjusting the total iron content of the target cast aluminum-silicon alloy to be 0.0-0.5%; The flux contains NaCl and KCl, wherein the mass fraction of NaCl is 45.0-45.5%, the mass fraction of KCl is 54.5-55.0%, and the amount of the flux added is 0.65-0.70wt% of the mass of the scrap aluminum; The amount of the refinement modifier added is 1.8-2.5% of the mass of the scrap aluminum; The target temperature of the temperature increasing step is 740-770°C.

8. The use according to claim 7, characterized in that: The preheating temperature of the preheating step is 250-350° C., and the preheating time is 1-2 hours.

9. A method for preparing a cast aluminum-silicon alloy, characterized in that: include: The cast aluminum-silicon alloy melt according to claim 7 or 8 is subjected to component detection, component blending treatment, refining treatment, slag removal treatment, heat preservation treatment, casting treatment and heat treatment; The composition detection analyzes the content of Al, Si, Mg and Fe elements in the melt.

10. The method for preparing a cast aluminum-silicon alloy according to claim 9, characterized in that: The heat treatment is divided into solution treatment and aging stages; wherein the solution treatment stage comprises heating the cast recycled aluminum product at 500-540°C for 4-6 hours, and then immediately immersing it in water for rapid cooling; the aging stage comprises heating the rapidly cooled recycled aluminum product at 160-190°C for 5-8 hours, and then taking it out for rapid cooling.

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