Steel / aluminum composite bimetallic casting method applied to sacrificial anode

Abstract

The invention belongs to the technical field of liquid-solid composite casting of nuclear power stations, aims to solve the problems that in the service period of a sacrificial anode, due to the fact that an iron core and an anode interface are not firmly combined, the anode is locally corroded and falls off from a pipeline, and discloses a steel / aluminum composite bimetal casting method applied to the sacrificial anode. The method comprises the following steps: sequentially carrying out polishing, alkali washing, water washing, acid washing and water washing treatment on an iron core, immersing the iron core in a plating assisting solution containing potassium fluozirconate, potassium chloride and sodium fluoride, carrying out constant-temperature water bath heat preservation, drying to finish pretreatment, immersing the pretreated iron core in a pure aluminum melt for dip plating, synchronously smelting an aluminum sacrificial anode alloy, fixing the dip-plated iron core in a preheated iron mold, and carrying out heat preservation and heat preservation on the iron core. And casting the alloy liquid and then demoulding and forming. According to the method, the steel / aluminum interface casting defects such as holes and cracks can be reduced, the interface bonding strength and the interface integrity of the steel / aluminum composite bimetal are improved, and therefore the long-period and stable discharging performance of the aluminum sacrificial anode is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid-solid composite casting of nuclear power plants, and particularly relates to a steel / aluminum composite bimetal casting method applied to a sacrificial anode. BACKGROUND

[0002] Aluminum sacrificial anodes are often used as cathodes to protect pipelines in coastal nuclear power plants. During installation, the iron core is connected to the pipeline. Due to the high salt content and chloride ion content in seawater, if there are gaps, holes or cracks at the connection between the iron core and the sacrificial anode, galvanic corrosion will occur to the sacrificial anode and the iron core, and will expand along the interface, ultimately leading to unstable connection of the iron core and the sacrificial anode and falling off, causing damage to the equipment. Therefore, when preparing the aluminum sacrificial anode, it is necessary to ensure that the interface between the iron core and the aluminum sacrificial anode is tightly combined without cracks or holes, has a large shear strength and strong corrosion resistance, so that the sacrificial anode will not fall off prematurely to cause accidents.

[0003] Currently, the steel / aluminum composite casting technology generally uses surface pretreatment to improve the wettability of the metal in a high-temperature state, such as using sandblasting, polishing or organic solvent cleaning to remove the surface oxide layer, and the increase in surface roughness also helps to improve the wettability of the substrate. However, these methods still have some shortcomings, such as a large number of cracks and holes in the metallurgical bonding layer, poor combination, small shear strength, and poor combination performance, which cannot meet the service performance.

[0004] Liquid-solid composite casting technology is a new type of bimetal composite technology. The prepared bimetal has superior performance that cannot be met by a single metal. It has the advantages of both metals and can improve their respective shortcomings, and the interface is tightly combined. Its principle is to pour molten metal onto a metal with a higher melting point. Under the action of high temperature, a certain thickness of metallurgical layer is formed through element diffusion between the two metals. The main component is intermetallic compound, which improves the bonding strength of the composite bimetal, thereby obtaining a composite material with better performance.

[0005] In the prior art, Chinese patent CN115141997A discloses an aluminum-steel bimetallic composite material and a preparation method thereof. The preparation method is to first use an aluminum-silicon alloy melt to dip coat a steel substrate, and then pour an aluminum-silicon alloy melt with the same composition as the dip coating liquid on the steel substrate. However, the shear strength of the aluminum-steel bimetal prepared by this method is low, only 35Mpa. In addition, Chinese patent CN113789454A discloses a method for aluminum-steel solid-liquid bimetal composite casting. The method uses ultrasonic vibration to promote metallurgical bonding during hot dip coating. The shear strength of the final composite metal can reach 60Mpa. However, the method is complicated and not suitable for industrial production. SUMMARY

[0006] The application aims to provide a steel / aluminum composite bimetal casting method applied to a sacrificial anode, solve the problem that the sacrificial anode is partially corroded and falls off from a pipeline due to the poor combination of the iron core and the anode interface during service, and ensure that the sacrificial anode can work effectively for a long time.

[0007] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0008] A steel / aluminum composite bimetal casting method applied to a sacrificial anode, comprising:

[0009] Step 1, polish, alkali wash, water wash, acid wash and water wash the iron core in sequence, immerse the iron core in a plating aid solution containing potassium fluozirconate, potassium chloride and sodium fluoride, and perform constant temperature water bath heat preservation, and then dry to complete the pretreatment;

[0010] Step 2, immerse the pretreated iron core in a pure aluminum melt for immersion plating, simultaneously smelt an aluminum sacrificial anode alloy, fix the immersion plated iron core in a preheated iron mold, and then cast the alloy liquid and demold to form.

[0011] As an implementable mode, step 1 comprises:

[0012] Step 1.1, polish the iron core with sandpaper, then put the iron core in a 10% sodium hydroxide solution for alkali washing, and then wash with water;

[0013] Step 1.2, put the iron core in a 10% sulfuric acid solution for acid washing, and then wash with water;

[0014] Step 1.3, perform plating aid pretreatment on the iron core in the plating aid solution;

[0015] Step 1.4, perform heat preservation in a constant temperature water bath;

[0016] Step 1.5, put the iron core in an oven for drying at 100℃-130℃, and the drying time is 10 minutes-20 minutes.

[0017] As an implementable mode, in step 1.1, the iron core is a strip-shaped iron core made of Q235.

[0018] As an implementable mode, in step 1.3, the plating aid solution comprises potassium fluozirconate 40g / L-60g / L, potassium chloride 40g / L-60g / L and sodium fluoride 1g / L-3g / L.

[0019] As an implementable mode, in step 1.4, the temperature is controlled at 80℃-100℃, and the plating aid soaking time is 2 minutes-10 minutes.

[0020] As an implementable mode, in step 1.5, the drying temperature is 100℃-130℃, and the drying time is 10 minutes-20 minutes.

[0021] As an implementable way, step 2 comprises:

[0022] Step 2.1: Put the pretreated iron core into the immersion of pure aluminum liquid for immersion plating;

[0023] Step 2.2: According to the alloy composition design of the sacrificial anode, the pickling ingredients are prepared, smelting and adding covering agent, after melting, adding alloying elements and covering agent, after complete melting, stirring, standing, adding refining agent to degas, after standing, slagging, to obtain bright molten aluminum alloy liquid;

[0024] Step 2.3: Put the iron core after immersion plating into the iron mold preheated to 400-450 DEG C and fix it, then pour the molten aluminum sacrificial anode alloy liquid into the iron mold, and get the steel / aluminum composite bimetal after demolding.

[0025] As an implementable way, in step 2.1, the immersion plating temperature is 780-800 DEG C, and the immersion plating time is 3-15 minutes.

[0026] As an implementable way, step 2.2 comprises:

[0027] Using pure aluminum and other required alloying elements (including aluminum, zinc, indium, magnesium, titanium) as raw materials, the pickling ingredients are prepared according to the alloy composition design;

[0028] Smelting, adding pure aluminum ingot into the graphite crucible and scattering covering agent, heating the smelting furnace to 780-820 DEG C, then adding other alloying elements (including aluminum, zinc, indium, magnesium, titanium) after the pure aluminum ingot is completely melted, while scattering covering agent, stirring and standing after all alloying elements are completely melted;

[0029] Adding refining agent to degas, after standing for 5-10 minutes, slagging to obtain bright molten aluminum alloy liquid.

[0030] As an implementable way, in step 2.3, the iron mold is preheated to 400-450 DEG C.

[0031] Compared with the prior art, the steel / aluminum composite bimetal casting method applied to the sacrificial anode provided by the application has the following beneficial effects:

[0032] The application proposes a steel / aluminum composite bimetal casting method applied to the sacrificial anode, which can reduce casting defects such as holes, cracks and steel / aluminum interface, improve the interface bonding strength and interface integrity of the steel / aluminum composite bimetal, so as to ensure the long-period and stable discharge performance of the aluminum sacrificial anode.

[0033] The steel / aluminum composite bimetal interface prepared by the application is combined tightly without casting defects such as holes and cracks, the shear strength is 44-50 MPa, the production process is simple, easy to operate and low in cost.

[0034] The application can effectively prevent the aluminum sacrificial anode from falling off caused by the corrosion of the steel / aluminum interface, and significantly improve the use safety of the aluminum sacrificial anode.

[0035] Further, the application designs a preparation process of strengthening the metallurgical combination of steel / aluminum by carrying out hot-dip surface treatment on the steel to solve the problems of many interface defects and insufficient strength of the steel / aluminum, including aluminum alloy smelting, steel plating pretreatment, steel hot-dip plating and steel / aluminum composite bimetal casting, so that the steel / aluminum composite bimetal with stable metallurgical interface combination can be obtained.

[0036] Further, the application designs the ratio of potassium fluozirconate, potassium chloride and sodium fluoride in the steel substrate plating solution, and carries out plating operation in a constant temperature water bath at 80-100 DEG C, so that the wettability of the steel substrate surface can be effectively improved, and the oxidation of the steel substrate at high temperature can be prevented, and the steel / aluminum interface combination can be promoted.

[0037] Further, the application provides a composite casting technology cooperating with the smelting process and the hot-dip plating process, the iron core hot-dip plating operation is simultaneously carried out in the sacrificial anode alloy smelting process, and the sacrificial anode aluminum alloy and the aluminum-plated iron core are poured together, so that the cooling of the iron core during pouring can be effectively reduced, and the combination of the iron core and the sacrificial anode aluminum alloy can be improved, the hot-dip plating and the aluminum alloy smelting can be simultaneously carried out, and then the pouring is carried out together in the mold, so that the process and the cost can be greatly saved. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed to be used in the technical description.

[0039] Figure 1 The flow chart of the steel / aluminum composite bimetal casting method for the sacrificial anode provided by the application is shown in the figure;

[0040] Figure 2 The steel / aluminum composite bimetal macroscopic morphology schematic diagram provided by the embodiment 1 of the application is shown in the figure;

[0041] Figure 3 The steel / aluminum composite interface microstructure morphology schematic diagram provided by the embodiment 1 of the application is shown in the figure;

[0042] Figure 4 The EDS element scanning diagram provided by the embodiment 1 of the application is shown in the figure;

[0043] Figure 5 The steel / aluminum composite interface microstructure morphology schematic diagram provided by the embodiment 2 of the application is shown in the figure;

[0044] Figure 6 A schematic diagram of the microstructure morphology of the steel / aluminum composite interface provided for Embodiment 3 of the present application is shown in Figure 3.

[0045] Figure 7 A schematic diagram of the microstructure morphology of the steel / aluminum composite interface provided for Embodiment 4 of the present application is shown in Figure 4. DETAILED DESCRIPTION

[0046] The application will be further described in detail through specific embodiments.

[0047] As shown in Figure 1, the present application provides a steel / aluminum composite bimetal casting method applied to a sacrificial anode, which comprises: Figure 1

[0048] Step 1: sequentially polish, alkali wash, water wash, acid wash, and water wash the iron core, immerse it in a plating aid solution containing potassium fluozirconate, potassium chloride, and sodium fluoride for constant temperature water bath heat preservation, dry to complete pretreatment;

[0049] Step 2: immerse the pretreated iron core in a pure aluminum melt for immersion plating, simultaneously smelt an aluminum sacrificial anode alloy, fix the immersion plated iron core in a preheated iron mold, and after pouring the alloy liquid, demold to form.

[0050] Specifically, Step 1 comprises:

[0051] Step 1.1: polish the strip-shaped iron core with a material of Q235 with 800-mesh sandpaper, then put it in a 10% sodium hydroxide solution for alkali washing for 10 minutes, and water wash. Through Step 1.1, the oil stains on the surface of the steel substrate can be effectively removed, which helps to improve the adhesion of the substrate to the plating aid solution in the subsequent plating aid step.

[0052] Step 1.2: put the iron core in a 10% sulfuric acid solution for acid washing for 10 minutes, and water wash. Through Step 1.2, the oxide scale on the surface of the steel substrate can be effectively removed, which helps to improve the adhesion of the substrate to the plating aid solution in the subsequent plating aid step.

[0053] Step 1.3: after water washing of the iron core, perform plating aid pretreatment in a plating aid solution. The composition of the plating aid solution is potassium fluozirconate 40-60 g / L, potassium chloride 40-60 g / L, and sodium fluoride 1-3 g / L. The plating aid solution used in Step 1.3 can crystallize and adhere to the surface of the steel substrate, forming a thin salt protective layer, which effectively prevents the steel substrate from being oxidized during the hot dipping plating process, and improves the bonding of the steel substrate to the pure aluminum plating solution.

[0054] Step 1.4: heat preservation in a constant temperature water bath, temperature control at 80-100℃, plating aid soaking time for 2-10 minutes. The plating aid temperature and time used in Step 1.4 can control the efficient crystallization of the plating aid solution on the surface of the steel substrate, forming a thin salt protective layer, preventing the steel substrate from being oxidized during the subsequent hot dipping plating process, and improving the bonding of the steel substrate to the pure aluminum plating solution. ​

[0055] Step 1.5: Put the iron core into the oven for drying at 100-130℃ for 10-20 minutes.

[0056] Specifically, step 2 includes:

[0057] Step 2.1: Dip the pretreated iron core into pure aluminum liquid for immersion plating, with the temperature controlled at 780-800℃ and the time controlled at 3-15 minutes. The melting temperature of the pure aluminum liquid in step 2.1 is consistent with that of the sacrificial anode aluminum alloy, so that the hot-dip plating operation can be synchronized with the smelting operation of the sacrificial anode, greatly saving the process and cost. Moreover, the hot-dip plating of the steel substrate at this temperature and time can make the steel substrate and the aluminum plating layer have greater bonding force and more stable combination.

[0058] Step 2.2: Use pure aluminum and other alloy elements (aluminum, zinc, indium, magnesium, titanium) as raw materials, and perform pickling and batching according to the alloy composition design (aluminum sacrificial anode alloy composition design); use a high-frequency induction melting furnace to smelt, add pure aluminum ingots and cover agents into a graphite crucible, heat the melting furnace to 780-820℃, add other alloy elements (aluminum, zinc, indium, magnesium, titanium) after the pure aluminum ingots are completely melted, and at the same time, add cover agents, stir with a graphite rod for 5 minutes after all the alloy elements are completely melted, and then stand for 5-10 minutes, then add refining agents to degas, stand for another 5-10 minutes, and then take out the slag to obtain a molten aluminum alloy liquid with a bright surface.

[0059] In step 2.2, the smelting operation in the range of 780-820℃ can effectively improve the alloy smelting efficiency, the cover agent can effectively prevent excessive burning loss and oxidation of the metal during the heating and melting process, and the steps of stirring and degassing and taking out the slag can reduce impurities such as oxide inclusions and pores in the alloy, and improve the purity of the alloy and the quality of the ingot.

[0060] Step 2.3: Put the iron core after immersion plating into an iron mold preheated to 400-450℃ for fixation, then pour the molten aluminum sacrificial anode alloy liquid into the iron mold, and obtain a steel / aluminum composite bimetal after demolding. Step 2.3 can effectively maintain the temperature of the iron core with an aluminum plating layer during the pouring process, so that it is poured synchronously with the aluminum sacrificial anode, reduces the temperature difference between the iron core and the aluminum melt, and achieves better steel / aluminum interface bonding.

[0061] Example 1

[0062] In this example, an aluminum alloy is smelted by using a high-frequency induction melting furnace, and the smelting temperature is 800℃. The alloy obtained by smelting at this temperature has a uniform structure without obvious pores and defects. The operation steps of this example are as follows:

[0063] The strip-shaped iron core made of Q235 is polished with 800 mesh sandpaper, then put into 10% sodium hydroxide solution for alkaline washing for 10 minutes, and then washed with water; then the iron core is put into 10% sulfuric acid solution for acid washing for 10 minutes, and then washed with water. This step can effectively remove the oil stains and oxide skin on the surface of the steel substrate, which helps to improve the adhesion of the substrate to the plating solution in the subsequent plating assisting step.

[0064] After the water washing of the iron core is completed, the iron core is put into the plating assisting solution for plating assisting pretreatment. The composition of the plating assisting solution is potassium fluozirconate 50 g / L; potassium chloride 50 g / L, sodium fluoride 1 g / L. The plating assisting solution is kept in a constant temperature water bath, and the temperature is controlled at 80°C. The plating assisting soaking time is 10 minutes. This plating assisting process can form a uniform and thin salt crystal layer on the surface of the steel substrate, which can effectively prevent the oxidation of the steel substrate during hot dipping plating and improve the adhesion of the plating layer.

[0065] After the plating assisting is completed, the iron core is taken out and put into an oven for drying at 110°C for 30 minutes, and then the pretreated iron core is immersed in molten pure aluminum liquid for immersion plating. The immersion plating temperature is controlled at 780°C, and the immersion plating time is 3 minutes, which can cover the surface of the steel substrate with a pure aluminum plating layer, so that it can be co-cast with the sacrificial anode aluminum alloy during casting, and the combination is tight. After the immersion plating is completed, the iron core is put into an iron mold preheated to 400°C for fixation, and then molten aluminum alloy is poured into the iron mold. After demolding, a steel / aluminum composite bimetal is obtained.

[0066] After cooling to room temperature, the microstructure is tested by sampling. The macrostructure of the composite metal is shown in Figure 2 The microstructure and element distribution of the steel / aluminum composite interface are shown in Figure 3 、 Figure 4 The compound generated at the interface is Al3Fe, as shown by energy spectrum analysis.

[0067] The interface shear strength of the composite metal is 50Mpa.

[0068] Example 2

[0069] In this example, the aluminum alloy is melted by a high-frequency induction melting furnace, and the melting temperature is 820°C. At this temperature, the melting time is shortened, and the melting efficiency is improved. The operation steps of this example are as follows:

[0070] The strip-shaped iron core made of Q235 is polished with 800 mesh sandpaper, then put into 10% sodium hydroxide solution for alkaline washing for 10 minutes, and then washed with water; then the iron core is put into 10% sulfuric acid solution for acid washing for 10 minutes, and then washed with water.

[0071] After the core is washed with water, it is put into a plating assisting solution for plating assisting pretreatment. The plating assisting solution has a composition of potassium fluozirconate 40 g / L, potassium chloride 40 g / L, and sodium fluoride 1 g / L. The plating assisting solution is kept in a constant temperature water bath, and the temperature is controlled at 90°C. The plating assisting soaking time is 5 minutes. The plating assisting process increases the plating assisting temperature and improves the plating assisting efficiency.

[0072] After the plating assisting is completed, the core is taken out and put into an oven for drying at 110°C for 30 minutes. Then, the pretreated core is immersed into a molten pure aluminum liquid for immersion plating. The immersion plating temperature is controlled at 800°C, and the immersion plating time is 6 minutes. After the immersion plating is completed, the core is put into an iron mold preheated at 400°C for fixing. Then, a molten aluminum alloy is poured into the iron mold. After demolding, a steel / aluminum composite bimetal is obtained.

[0073] After being cooled to room temperature, the sample is taken for testing. The microscopic structure of the steel / aluminum composite interface is shown in FIG. 1. Figure 5

[0074] The interface shear strength of the composite metal is 47 MPa.

[0075] Example 3

[0076] In this example, an aluminum alloy is smelted by using a high-frequency induction smelting furnace. The smelting temperature is 780°C. At this smelting temperature, the loss of alloying elements is the least. The operation steps of this example are as follows:

[0077] After the strip-shaped core made of Q235 is polished by using 800-mesh sandpaper, it is put into a 10% sodium hydroxide solution for alkaline washing for 10 minutes, and then washed with water. Then, the core is put into a 10% sulfuric acid solution for acid washing for 10 minutes, and then washed with water.

[0078] After the core is washed with water, it is put into a plating assisting solution for plating assisting pretreatment. The plating assisting solution has a composition of potassium fluozirconate 60 g / L, potassium chloride 60 g / L, and sodium fluoride 2 g / L. The plating assisting solution is kept in a constant temperature water bath, and the temperature is controlled at 90°C. The plating assisting soaking time is 2 minutes. The plating assisting process increases the concentrations of potassium fluozirconate, potassium chloride, and sodium fluoride, and improves the plating assisting efficiency.

[0079] After the plating assisting is completed, the core is taken out and put into an oven for drying at 110°C for 30 minutes. Then, the pretreated core is immersed into a molten pure aluminum liquid for immersion plating. The immersion plating temperature is controlled at 800°C, and the immersion plating time is 9 minutes. After the immersion plating is completed, the core is put into an iron mold preheated at 400°C for fixing. Then, a molten aluminum alloy is poured into the iron mold. After demolding, a steel / aluminum composite bimetal is obtained.

[0080] After being cooled to room temperature, the sample is taken for testing. The microscopic structure of the steel / aluminum composite interface is shown in FIG. 1. Figure 6

[0081] The interface shear strength of the composite metal is 44 MPa.​​

[0082] Example 4

[0083] This example uses a high-frequency induction melting furnace to smelt aluminum alloy, and the smelting temperature is 800℃. The alloy obtained by smelting at this temperature is uniform in structure and has no obvious holes and defects. The operation steps of this example are as follows:

[0084] After the Q235 strip-shaped iron core is polished with 800-mesh sandpaper, it is placed in a 10% sodium hydroxide solution for alkaline washing for 10 minutes, and then washed with water. Then the iron core is placed in a 10% sulfuric acid solution for acid washing for 10 minutes, and then washed with water. After the water washing of the iron core is completed, the iron core is placed in a plating aid solution for plating aid pretreatment. The composition of the plating aid solution is potassium fluozirconate 50g / L; potassium chloride 40g / L, sodium fluoride 1g / L. The plating aid solution is kept warm in a constant temperature water bath, and the temperature is controlled at 85℃. The plating aid soaking time is 8 minutes. This plating aid process improves the uniformity and thickness of the thin salt crystal layer on the surface of the steel substrate, and more effectively prevents the oxidation of the steel substrate during hot dipping plating, and improves the bonding with the plating layer.

[0085] After the plating aid is completed, the iron core is taken out and placed in an oven for drying at 110℃ for 30 minutes, and then the pretreated iron core is immersed in molten pure aluminum liquid for immersion plating, and the immersion plating temperature is controlled at 780℃, and the immersion plating time is 12 minutes; this process reduces the immersion plating temperature, prolongs the hot dipping plating time, increases the thickness of the aluminum plating layer, and improves the steel / aluminum bonding strength. After the immersion plating is completed, the iron core is placed in a preheated 400℃ iron mold for fixation, and then molten aluminum alloy is poured into the iron mold, and after demolding, a steel / aluminum composite bimetal is obtained.

[0086] After cooling to room temperature, the sample is tested. The microstructure morphology of the steel / aluminum composite interface is as shown in Figure 7 .

[0087] The interface shear strength of the composite metal is 49Mpa.

[0088] The interface shear strength of the steel / aluminum composite bimetal of the above four examples is as follows:

[0089] Table 1 Interface shear strength of steel / aluminum composite bimetal

[0090] Example Example 1 Example 2 Example 3 Example 4 Shear strength / Mpa 50 47 44 49

[0091] Compared with the prior art, the process flow of the method is simple, the production cost is low, the steel / aluminum composite bimetal prepared has no interface casting defects such as holes and cracks, and the interface bonding strength and interface integrity of the steel / aluminum composite bimetal are greatly improved. The specific comparison is as follows:

[0092] (1) Compared with traditional composite casting technology, the method uses liquid-solid composite casting technology to prepare steel / aluminum composite bimetal, without interface casting defects such as pores and cracks, and good metallurgical bonding effect is achieved, and the prepared steel / aluminum composite bimetal has higher interface shear strength.

[0093] (2) Compared with other liquid-solid composite casting technologies, the method has simple preparation process and low cost. The method combines aluminum alloy melting technology and hot dipping technology, reduces the oxidation of the surface of the steel matrix, and ensures the wettability of the steel / aluminum interface.

[0094] (3) Compared with other hot dipping processes, the method uses a self-prepared plating aid liquid. The plating aid liquid can effectively improve the wettability of the steel matrix, activate the surface of the steel matrix, and reduce the surface oxidation, and improve the stability of the steel / aluminum hot dipping interface metallurgical bonding.

[0095] (4) The method reduces the casting defects of the interface, effectively prevents the aluminum sacrificial anode from falling off caused by interface corrosion, and significantly improves the use safety of the aluminum sacrificial anode.

[0096] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A steel / aluminum clad bimetal casting method applied to a sacrificial anode, characterized by, The application relates to a method for preparing a steel / aluminum composite bimetal. The method comprises the following steps: Step 1: polishing, alkali washing, water washing, acid washing, water washing and treatment of the iron core in sequence, immersing the iron core into a plating-aiding solution containing potassium fluozirconate, potassium chloride and sodium fluoride for constant-temperature water bath heat preservation, and drying to complete the pretreatment; 2. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 1, characterized in that, Step 2: immersing the pretreated iron core into a pure aluminum melt for immersion plating, synchronously smelting an aluminum sacrificial anode alloy, fixing the immersion plated iron core in a preheated iron mold, and casting the alloy liquid to form a steel / aluminum composite bimetal after demolding. Step 1 comprises the following steps: Step 1.1: polishing the iron core with sandpaper, then placing the iron core into a 10% sodium hydroxide solution for alkali washing, and then water washing; Step 1.2: placing the iron core into a 10% sulfuric acid solution for acid washing, and then water washing; Step 1.3: placing the iron core into a plating-aiding solution for plating-aiding pretreatment; Step 1.4: heat preservation in a constant-temperature water bath; 3. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 2, characterized in that, Step 1.5: placing the iron core into an oven for drying at 100-130 DEG C, and the drying time is 10-20 minutes.

4. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 2, characterized in that, In step 1.1, the iron core is a strip-shaped iron core made of Q235.

5. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 2, characterized in that, In step 1.3, the plating-aiding solution comprises 40-60 g / L of potassium fluozirconate, 40-60 g / L of potassium chloride and 1-3 g / L of sodium fluoride.

6. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 2, characterized in that, In step 1.4, the temperature is controlled at 80-100 DEG C, and the plating-aiding soaking time is 2-10 minutes.

7. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 1, characterized in that, In step 1.5, the drying temperature is 100-130 DEG C, and the drying time is 10-20 minutes. Step 2 comprises the following steps: Step 2.1: immersing the pretreated iron core into a pure aluminum liquid for immersion plating; Step 2.2: acid washing, ingredient preparation, smelting and adding covering agent according to the alloy composition of the sacrificial anode, adding alloy elements and covering agent after melting, stirring and standing after complete melting, adding refining agent for degassing, and obtaining bright molten aluminum alloy liquid after slagging; 8. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 7, characterized in that, Step 2.3: placing the immersion plated iron core into an iron mold preheated to 400-450 DEG C for fixing, then pouring the molten aluminum sacrificial anode alloy liquid into the iron mold, and obtaining a steel / aluminum composite bimetal after demolding.

9. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 7, characterized in that, In step 2.1, the immersion plating temperature is 780-800 DEG C, and the immersion plating time is 3-15 minutes. Step 2.2 comprises the following steps: Using pure aluminum and required alloy elements as raw materials, and preparing ingredients according to the alloy composition design; Smelting, adding pure aluminum ingot into a graphite crucible and scattering covering agent, heating the smelting furnace to 780-820 DEG C, then adding alloy elements after complete melting of the pure aluminum ingot, and scattering covering agent, stirring and standing after complete melting of all the alloy elements; 10. The steel / aluminum clad bimetal casting method for a sacrificial anode according to claim 7, characterized in that, Adding refining agent for degassing, and obtaining bright molten aluminum alloy liquid after slagging after 5-10 minutes of standing. In step 2.3, the iron mold is preheated to 400-450 DEG C.

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