Preparation method of copper-silicon intermediate alloy and method for preparing aluminum-copper-silicon alloy by using intermediate alloy

Abstract

The invention belongs to the technical field of casting, and particularly relates to a preparation method of a copper-silicon intermediate alloy and a method for preparing an aluminum-copper-silicon alloy by using the intermediate alloy, and the method comprises the following steps: 1) preparing red copper and crystalline silicon; 2) preheating a crucible furnace to 600-700 DEG C, firstly adding part of crystalline silicon and covering the bottom of the crucible furnace, and then adding part of red copper to cover the crystalline silicon; (3) the furnace temperature is increased to 1150-1250 DEG C, and after the red copper in the crucible furnace is completely melted, the remaining red copper and crystalline silicon are added; (4) after the red copper newly added into the crucible furnace is completely melted, a layer of dry charcoal is laid on the surface of the furnace material; and 5) raising the furnace temperature to 1300-1450 DEG C, stirring until the crystalline silicon is completely molten, continuously stirring for a period of time, keeping the temperature, standing, slagging off, discharging from the furnace, and pouring a casting mold to obtain the copper-silicon intermediate alloy. The smelting method is simple and convenient in process and short in time, reduces the production cost of factories and the working intensity of workers, has few impurities and improves the purity of the alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of casting, and in particular relates to a method for preparing a copper-silicon master alloy and a method for preparing an aluminum-copper-silicon alloy by using the master alloy. Background Art

[0002] Aluminum-copper-silicon alloy is a cast aluminum alloy with aluminum as the matrix element and copper and silicon as the main alloying elements. It is a lightweight, high-strength metal material. This material has good air tightness, machinability and weldability. It is mainly used for parts with medium or impact loads in the fields of automobiles, ships, aerospace, etc., such as brackets, crankcases, flywheel covers, etc., and has high economic value.

[0003] The traditional aluminum-copper-silicon alloy is first smelted in a graphite crucible, cut into small pieces for later use, and then the aluminum-copper intermediate alloy, pure aluminum and crystalline silicon are melted together until they are evenly melted and poured to obtain the aluminum-copper-silicon alloy. This method has a cumbersome smelting process, and the calculation of the content of each component is complicated, which is difficult to control when feeding. In addition, due to the high melting point of silicon and high smelting temperature, this smelting method has a long production cycle and there is a risk that the silicon block cannot be completely melted, affecting the purity of the aluminum liquid. After being poured into a casting, the silicon block has a very high hardness and can damage the machine during cutting. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a copper-silicon master alloy and a method for preparing an aluminum-copper-silicon alloy using the master alloy, which has a simple process and a short time, reduces factory production costs and worker workload, and has fewer impurities and improves alloy purity.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing a copper-silicon alloy comprises the following steps:

[0007] 1) Prepare 75-80 parts of copper and 20-25 parts of crystalline silicon by weight;

[0008] 2) Preheat the crucible furnace to 600°C to 700°C, first add some crystalline silicon to cover the bottom of the crucible furnace, and then add some copper to cover the crystalline silicon;

[0009] 3) Raise the temperature of the crucible furnace to 1150-1250° C., and after all the copper in the crucible furnace is melted, add the remaining copper and crystalline silicon;

[0010] 4) After all the newly added copper in the crucible furnace is melted, place a layer of dry charcoal on the surface of the charge;

[0011] 5) Raise the temperature of the crucible furnace to 1300-1450°C, stir with a graphite rod until all the crystalline silicon is melted, then continue stirring for a period of time and keep it warm and let it stand, remove the slag from the furnace and pour it into a casting mold, demold the ingot after solidification, and obtain a copper-silicon intermediate alloy.

[0012] Preferably, in step 2), the portion of copper is 50% to 60% of the total copper weight; the portion of crystalline silicon is 70% to 80% of the total crystalline silicon weight. Copper occupies a lot of crucible space. Basically, 60% of the copper block will occupy 80% of the crucible space. After the copper is melted into copper liquid, a lot of crucible space can be released. Therefore, the present invention adds copper and crystalline silicon in batches, and the heating speed of 50% to 60% of the copper is relatively fast when it is melted first. After the temperature rises, the copper and crystalline silicon added in the second batch are easier to melt.

[0013] Preferably, in step 4), the thickness of the dry charcoal is 10-20 mm. Laying the dry charcoal with the above thickness can prevent the absorption of moisture and air in the air during the heating process.

[0014] Preferably, in step 5), the stirring time is more than 5 minutes, and the heat preservation and standing time is 5 to 10 minutes.

[0015] Preferably, in step 5), the surface of the casting mold is coated with a coating; the coating comprises 25wt% to 30wt% zinc oxide, 3wt% to 5wt% water glass, and the remainder is water. Studies have shown that coating the surface of the casting mold with a layer of the coating can increase the fluidity of the molten metal when pouring the ingot, and prevent the ingot from sticking to the ingot mold after pouring.

[0016] Preferably, in step 5), the thickness of the copper-silicon intermediate alloy is less than 30 mm.

[0017] The present invention also provides a method for preparing an aluminum-copper-silicon alloy, comprising the following steps:

[0018] 1) preparing a copper-silicon master alloy using the above-mentioned method for preparing a copper-silicon master alloy;

[0019] 2) Putting the copper-silicon master alloy and aluminum ingot prepared in step 1) into a melting furnace for smelting to obtain aluminum-copper-silicon alloy.

[0020] Preferably, the mass ratio of the copper-silicon master alloy to the aluminum ingot is 1-1.2:2.8-3.2.

[0021] The beneficial effects of the present invention are at least:

[0022] 1) The present invention provides a method for preparing a copper-silicon master alloy and a method for preparing an aluminum-copper-silicon alloy using the master alloy. Crystalline silicon and a copper block are first melted to form a copper-silicon master alloy. The melting point of the alloy is reduced, and the time required for smelting in the actual production of castings is significantly shortened, thereby reducing the factory production cost and the work intensity of workers;

[0023] 2) The present invention provides a method for preparing a copper-silicon master alloy and a method for preparing an aluminum-copper-silicon alloy using the master alloy, wherein the aluminum-copper-silicon alloy obtained has less impurities and the purity of the alloy is improved;

[0024] 3) The present invention provides a method for preparing a copper-silicon master alloy and a method for preparing an aluminum-copper-silicon alloy using the master alloy, wherein copper and crystalline silicon are added in batches to make the copper and crystalline silicon easier to melt;

[0025] 4) The present invention provides a method for preparing a copper-silicon intermediate alloy and a method for preparing an aluminum-copper-silicon alloy using the intermediate alloy. The surface of the casting mold is coated with a layer of coating composed of zinc oxide, water glass and water, which can increase the fluidity of the molten metal when pouring the ingot and prevent the ingot from sticking to the ingot mold after pouring. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used.

[0027] In the following examples, information of the raw materials used is shown in Table 1.

[0028] Table 1 Raw material information used in the examples

[0029]

[0030] Example 1

[0031] A method for preparing a copper-silicon master alloy comprises the following steps:

[0032] 1) Prepare 240 kg copper plate and 60 kg crystalline silicon by weight, cut the copper plate into a size less than 160 mm × 100 mm, and crush the crystalline silicon into blocks of about 10 mm (the block size is the maximum distance between the two ends) for standby use;

[0033] 2) Preheat the coke crucible furnace to 650° C. First, add 48 kg of crystalline silicon to cover the bottom of the coke crucible furnace, and then add 144 kg of copper to cover the crystalline silicon;

[0034] 3) Raise the furnace temperature to 1200°C, and after all the copper in the coke crucible furnace is melted, add the remaining crystalline silicon and copper;

[0035] 4) After all the newly added copper in the coke crucible furnace is melted, a layer of dry charcoal with a thickness of 20 mm is laid on the surface of the charge;

[0036] 5) Raise the temperature of the coke crucible furnace to 1400°C, stir with a graphite rod until the crystalline silicon is completely melted, then keep stirring for 5 minutes, let stand for 10 minutes, remove the slag from the furnace and pour into a casting mold (preheat the casting mold and coat the surface with a mixed coating composed of 26wt% zinc oxide, 4wt% water glass and 70wt% water) to obtain a copper-silicon intermediate alloy with a thickness of 30mm.

[0037] A method for preparing an aluminum-copper-silicon alloy, the specific steps are as follows:

[0038] 1) Preheat a 500kg crucible to 600℃ during smelting, add 262kg pure aluminum ingot (accounting for 60wt% of the total amount of pure aluminum ingot) and 63kg copper-silicon master alloy, and mix large and small pieces when loading, do not pack them too tightly, and the charge height should not exceed the crucible height;

[0039] 2) Raise the temperature to 750℃ to melt all the aluminum ingots. During the melting process, the liquid surface should always be covered (i.e., a layer of covering agent is laid, the covering agent comes from Shenyang Zhongbei Casting Materials Co., Ltd.). Add the remaining 175kg pure aluminum ingots, keeping the covering layer intact until the aluminum ingots are completely melted into liquid;

[0040] 3) When the power is turned off and the temperature drops to 730℃, scrape off the slag, add the refining flux hexachloroethane powder cake, press it in with a pressure scoop and stir vertically until the liquid surface is mirror-like and the flux and the alloy liquid are completely separated. The refining is completed, and the refining is allowed to stand for 15 minutes after refining;

[0041] 4) When the power is turned off and the temperature drops to 710℃, clean the slag and start pouring.

[0042] The impurity content of the aluminum-copper-silicon alloy prepared in Example 1 is 0.2%.

[0043] Comparative Example 1

[0044] Comparative Example 1 adopts a traditional smelting process, and the steps are as follows:

[0045] 1. Melting aluminum-copper master alloy

[0046] Melt the aluminum-copper master alloy in a graphite crucible, melt 90kg of pure aluminum ingots and superheat to 900℃, add 150kg of 100mm×100mm copper plates in batches after preheating, stir each batch thoroughly, and add the next batch after melting. After all the copper blocks are melted, add the remaining 60kg of aluminum ingots, stir thoroughly, degas and refine, and then pour the ingots. (Because the melting point of copper is 1083.4℃, use a 150KW / h resistance insulation furnace, the heating time takes 8 hours, and after adding copper plates in batches, the melting time is extended by 3 hours)

[0047] 2. Melting Aluminum-Silicon-Copper Alloy

[0048] 1) When smelting, preheat a 500kg crucible to 600℃, add 232kg pure aluminum ingot, 13kg crystalline silicon and 100kg aluminum-copper master alloy. The crystalline silicon needs to be preheated in advance, and the particle size is 20mm; the aluminum-copper master alloy is preheated in advance, and the block size is 300mm×100mm×30mm. When loading, large and small blocks should be matched, not too compact, and the charge height should not exceed the height of the crucible;

[0049] 2) Raise the temperature to 900℃ to melt the aluminum ingot completely. The liquid surface should always be covered during the melting process. Add 155kg of pure aluminum ingot, keeping the covering layer intact until the aluminum ingot is completely melted into liquid;

[0050] 3) Raise the temperature to 1400°C to melt all the crystalline silicon, and keep the liquid surface covered during the melting process;

[0051] 4) When the power is turned off and the temperature drops to 740℃, scrape off the slag, add refining flux, press it in with a pressure scoop and stir vertically until the liquid surface is mirror-like and the flux and alloy liquid are completely separated. Refining is completed. After refining, let it stand for 15 minutes;

[0052] 5) When the power is turned off and the temperature drops to 710℃, clean the slag and start pouring.

[0053] The impurity content of the aluminum-copper-silicon alloy prepared in Comparative Example 1 is 0.8%.

[0054] Table 2 Comparison of melting time between Example 1 and Comparative Example 1 (using the same equipment)

[0055] project Comparative Example 1 Example 1 Master alloy melting time 11h 11h Aluminum-copper-silicon alloy melting time 15h 6h

[0056] Table 3 Energy consumption comparison between Example 1 and Comparative Example 1 (equipment power 150kw / h)

[0057] project Comparative Example 1 Example 1 Master alloy melting time 1650kw 1650kw Aluminum-silicon-copper alloy melting time 2250kw 900kw

[0058] From the comparison of the results in Table 2 and Table 3, it can be seen that in Example 1, the crystalline silicon and the copper block are first melted to form a copper-silicon intermediate alloy, the melting point of the alloy is reduced, and the time required for smelting in the actual production of castings is significantly shortened; at the same time, the silicon element in the aluminum liquid in Example 1 is evenly mixed, and no silicon block impurities appear.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a copper-silicon master alloy, characterized in that: The following steps are involved: 1) Prepare 75-80 parts of copper and 20-25 parts of crystalline silicon by weight; 2) Preheat the crucible furnace to 600°C to 700°C, first add some crystalline silicon to cover the bottom of the crucible furnace, and then add some copper to cover the crystalline silicon; 3) Raise the temperature of the crucible furnace to 1150-1250° C., wait until all the copper in the crucible furnace is melted, stir evenly, and add the remaining copper and crystalline silicon; 4) After all the newly added copper in the crucible furnace is melted, place a layer of dry charcoal on the surface of the charge; 5) Raise the temperature of the crucible furnace to 1300-1450°C, stir with a graphite rod until all the crystalline silicon is melted, then continue stirring for a period of time and keep it warm and let it stand, remove the slag from the furnace and pour it into a casting mold, demold the ingot after solidification, and obtain a copper-silicon intermediate alloy.

2. The method for preparing the copper-silicon master alloy according to claim 1, characterized in that: In step 2), the portion of copper is 50% to 60% of the total copper weight; the portion of crystalline silicon is 70% to 80% of the total crystalline silicon weight. 。 3. The method for preparing the copper-silicon master alloy according to claim 1 or 2, characterized in that: In step 4), the thickness of the dried charcoal is 10 to 20 mm.

4. The method for preparing the copper-silicon master alloy according to claim 1 or 2, characterized in that: In step 5), the stirring time is more than 5 minutes, and the heat preservation and standing time is 5 to 10 minutes.

5. The method for preparing the copper-silicon master alloy according to claim 1 or 2, characterized in that: In step 5), a layer of coating is applied on the surface of the casting mold; the coating comprises 25wt% to 30wt% zinc oxide, 3wt% to 5wt% water glass, and the remainder is water.

6. The method for preparing the copper-silicon master alloy according to claim 1 or 2, characterized in that: In step 5), the thickness of the copper-silicon intermediate alloy is less than 30 mm.

7. A method for preparing an aluminum-copper-silicon alloy, characterized in that: The following steps are involved: 1) preparing a copper-silicon master alloy by using the method for preparing a copper-silicon master alloy according to any one of claims 1 to 6; 2) Putting the copper-silicon master alloy and aluminum ingot prepared in step 1) into a melting furnace for smelting to obtain aluminum-copper-silicon alloy.

8. The method for preparing the aluminum-copper-silicon alloy according to claim 7, characterized in that: The mass ratio of the copper-silicon master alloy to the aluminum ingot is 1-1.2:2.8-3.2.

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