Aluminum / iron double-metal composite material based on chemical nickel-plated layer and preparation method of aluminum / iron double-metal composite material

Abstract

The invention belongs to the technical field of composite material casting, and relates to an aluminum / iron double-metal composite material based on a chemical nickel-plating layer and a preparation method of the aluminum / iron double-metal composite material based on the chemical nickel-plating layer, a nickel layer with uniform thickness is preset on the surface of an iron base material in advance in a chemical plating mode, and the effect of thoroughly isolating direct contact between an aluminum material melt and the solid iron base material is achieved. The interface phase composition regulation and control of the aluminum / iron bimetallic composite material can be realized, the interface defects are greatly reduced, and the interface bonding strength is improved.

Description

Technical Field

[0001] The invention relates to the technical field of composite material casting, in particular to an aluminum / iron bimetallic composite material based on a chemical nickel plating layer and a preparation method thereof. Background Art

[0002] With the rapid development of the automotive industry, more and more stringent requirements are placed on the service performance of castings. However, taking automobile engines as an example, existing materials can no longer meet the gradually increasing design requirements. For example, aluminum alloy engines are prone to deformation and cracking, and it is difficult to guarantee a long-term working life under high temperature and high pressure. Although cast iron engines are suitable for long-term high-load conditions, their weight exceeds the standard. Therefore, it is urgent to find a reasonable solution to overcome the problem of no materials available for high-performance engines. Aluminum / iron bimetallic composite materials have become the best way to solve the problem because they take into account the advantages of both aluminum and iron. The main part of the engine is made of aluminum alloy to ensure lightweight, energy saving and environmental protection. The bearing part is made of cast iron to avoid deformation and cracking caused by crankshaft friction. The use of aluminum / iron bimetallic composite materials overcomes the shortcomings of traditional single metal materials in practical applications, and truly achieves cost reduction and efficiency improvement.

[0003] At present, the preparation method of aluminum / iron bimetallic composite materials for automobile engines is liquid-solid composite casting, that is, casting liquid aluminum alloy onto solid cast iron substrate. The metallurgical bonding of aluminum and iron interface is achieved through contact heat transfer during aluminum alloy casting, which improves the interface bonding strength. However, at the interface of aluminum / iron bimetallic composite materials, it is easy to form Al 13 Brittle intermetallic compounds such as Fe4, Al5Fe2, and Al2Fe directly lead to the aluminum / iron bimetallic composite material being very easy to crack at the interface during the casting process or in the service environment. Therefore, the brittle interface phase under the existing liquid-solid composite casting technology has become a shackle that restricts the further use of the aluminum / iron bimetallic composite material. In addition, the prior art uses an electroplating layer to isolate the direct contact between the aluminum / iron bimetallics, but due to the uneven current distribution, it is difficult to ensure uniform coating thickness, especially for complex components, electroplating cannot achieve stable deposition on all surfaces. Therefore, it is necessary to replace the electroplating technology to ensure the stability of the interface components of the aluminum / iron bimetallic composite material. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide an aluminum / iron bimetallic composite material based on a chemical nickel plating layer and a preparation method thereof.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions: A method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer comprises the following steps: S1. Surface treatment of the iron substrate; S2, preparing an intermediate layer on the surface of the iron substrate by chemical plating; S3, hot-dip plating treatment of an iron substrate with an intermediate layer prepared on the surface; S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate after hot-dip plating to obtain an aluminum / iron bimetallic composite material based on a chemical nickel plating layer.

[0006] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer according to the present invention, in step S1, the surface treatment includes degreasing, rust removal, and activation treatment, which specifically includes the following steps: S11. Use an electric grinder or shot peening machine to grind or shot peen the surface of the iron substrate until there is no black or yellow oxide and impurities on the surface to remove rust; S12, placing the iron substrate in a NaOH aqueous solution for ultrasonic cleaning to remove oil; S13, placing the iron substrate in an anhydrous ethanol solution for ultrasonic cleaning to remove residual NaOH; S14, placing the iron substrate in an HCl aqueous solution for ultrasonic cleaning to activate it; S15, placing the iron substrate in an anhydrous ethanol solution for ultrasonic cleaning to wash away the residual HCl; S16, drying the iron substrate.

[0007] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer described in the present invention, wherein: in the step S1, the iron substrate includes iron and steel, such as cast iron (such as ductile iron QT500), carbon steel (such as 20# steel), stainless steel (such as 42CrMo steel), etc.

[0008] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer according to the present invention, in step S2, the chemical plating process specifically includes the following steps: S21, placing the chemical plating solution in a container, and placing the container in a water bath; S22, placing the surface treated iron substrate into a prepared chemical plating solution for chemical plating; S23, immersing the chemically plated iron substrate in a Na2CO3 solution for alkaline cleaning; S24, placing the iron substrate in an anhydrous ethanol solution for ultrasonic cleaning; S25, drying the iron substrate.

[0009] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer according to the present invention, in step S2, the composition of the chemical plating solution is as follows: NiSO4·6H2O: 21~35g / L, NaH2PO2·H2O: 16~30g / L, NaC2H3O2: 2~6g / L, Na2CO3: 1~2.2g / L, CH3CHOHCOOH: 20~34g / L, the solvent is water.

[0010] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer described in the present invention, wherein: in the step S2, the pH value of the chemical plating solution is 5.0-6.5.

[0011] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer according to the present invention, in step S3, the hot dip plating process specifically comprises the following steps: S31, melting and heat-insulating the aluminum material for hot-dip coating to obtain an aluminum melt; S32, placing the iron substrate with the intermediate layer prepared on the surface into the aluminum melt; S33. Take out the iron substrate from the aluminum melt and observe the coating state of the aluminum melt; if the surface coating layer is bright silver, the surface is smooth and there is no leakage, it indicates that the hot-dip plating treatment is good; otherwise, the hot-dip plating treatment needs to be repeated.

[0012] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer described in the present invention, wherein: in the step S3, the aluminum material is pure aluminum or an aluminum alloy (such as an aluminum-silicon alloy such as ZL101A, ZL702A, an aluminum-copper alloy ZL205A, etc.).

[0013] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer according to the present invention, in step S4, the liquid-solid composite casting process specifically comprises the following steps: S41, melting the aluminum material for casting to obtain an aluminum melt, and then performing rotation degassing; S42, allowing the aluminum melt to stand still; S43, slagging the surface of the aluminum melt; S44, placing the hot-dip-plated iron substrate into a mold, pouring the molten aluminum into the mold, and completing the aluminum / iron bimetallic liquid-solid composite casting.

[0014] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer described in the present invention, in the step S4, the aluminum material is the same as the aluminum material used for hot-dip plating.

[0015] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution: An aluminum / iron bimetallic composite material based on a chemical nickel plating layer is prepared by adopting the preparation method of the aluminum / iron bimetallic composite material based on a chemical nickel plating layer.

[0016] As a preferred solution of the aluminum / iron bimetallic composite material based on chemical nickel plating layer described in the present invention, the intermediate layer is a nickel intermediate layer, and its thickness is 14-18 μm.

[0017] The beneficial effects of the present invention are as follows: The present invention provides an aluminum / iron bimetallic composite material based on a chemical nickel plating layer and a preparation method thereof. By chemical plating, a nickel layer with uniform thickness is pre-prepared on the surface of an iron substrate, which has the effect of completely isolating the direct contact between the aluminum melt and the solid iron substrate. The present invention can achieve the control of the interface phase composition of the aluminum / iron bimetallic composite material, greatly reduce interface defects, and improve the interface bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 This is a scanning electron microscope photograph of the metal interface of the aluminum / iron bimetallic composite material of Example 1 of the present invention; Figure 2 This is the result of energy spectrum analysis at the metal interface of the aluminum / iron bimetallic composite material of Example 1 of the present invention.

[0020] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. 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.

[0022] The present invention provides an aluminum / iron bimetallic composite material based on a chemical nickel plating layer and a preparation method thereof. A nickel layer with uniform thickness is pre-prepared on the surface of an iron substrate by chemical plating, which has the effect of completely isolating direct contact between the aluminum melt and the solid iron substrate.

[0023] According to one aspect of the present invention, the present invention provides the following technical solution: A method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer comprises the following steps: S1. Surface treatment of the iron substrate; S2, preparing an intermediate layer on the surface of the iron substrate by chemical plating; S3, hot-dip plating treatment of an iron substrate with an intermediate layer prepared on the surface; S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate after hot-dip plating to obtain an aluminum / iron bimetallic composite material based on a chemical nickel plating layer.

[0024] Preferably, in step S1, the surface treatment includes degreasing, rust removal, and activation treatment, which specifically includes the following steps: S11. Use an electric grinder or shot peening machine to grind or shot peen the surface of the iron substrate until there is no black or yellow oxide and impurities on the surface to remove rust; S12, placing the iron substrate in a 5.0-10.0wt% NaOH aqueous solution, and ultrasonically cleaning for 5-10 minutes to remove oil; S13, placing the iron substrate in anhydrous ethanol solution, and ultrasonically cleaning for 5-10 minutes to wash away the residual NaOH; S14, placing the iron substrate in a 5.0-10.0 wt% HCl aqueous solution, and ultrasonically cleaning for 5-10 min for activation; S15, placing the iron substrate in anhydrous ethanol solution, and ultrasonically cleaning for 5-10 minutes to wash away the residual HCl; S16, drying the iron substrate.

[0025] Preferably, in step S1, the iron substrate includes iron and steel, such as cast iron (such as ductile iron QT500), carbon steel (such as 20# steel), stainless steel (such as 42CrMo steel), etc. Further preferably, the iron substrate is ductile iron QT500, which has the characteristics of high yield strength, tensile strength, high temperature oxidation resistance, creep resistance, good high temperature strength, etc. In terms of weight percentage, its composition is C: 3.6~3.8wt%, Si: 2.5~2.9wt%, Mn<0.6wt%, S<0.025wt%, P<0.08wt%, Mg: 0.03~0.05wt%, RE: 0.03~0.05wt%, and the balance is Fe and unavoidable impurities.

[0026] Preferably, when the iron substrate is stainless steel, the concentrations of the NaOH aqueous solution and the HCl aqueous solution can be reduced, such as 5.0wt%; when the iron substrate is carbon steel, a medium concentration of the NaOH aqueous solution and the HCl aqueous solution can be selected, such as 7.0-8.0wt%; and when the iron substrate is cast iron, the concentrations of the NaOH aqueous solution and the HCl aqueous solution are increased, such as 10.0wt%.

[0027] Preferably, in step S2, the chemical plating process specifically includes the following steps: S21, placing the chemical plating solution in a container, and placing the container in a water bath; S22, placing the surface treated iron substrate into a prepared chemical plating solution, and performing chemical plating at a temperature of 80-100° C. for 10-15 minutes; S23, soaking the electrolessly plated iron substrate in a 10wt% Na2CO3 solution for 5-10 min for alkaline cleaning; S24, placing the iron substrate in anhydrous ethanol solution and ultrasonically cleaning for 5 to 10 minutes; S25, drying the iron substrate.

[0028] Preferably, in step S2, the composition of the chemical plating solution is as follows: NiSO4·6H2O: 21~35g / L, NaH2PO2·H2O: 16~30g / L, NaC2H3O2: 2~6g / L, Na2CO3: 1~2.2g / L, CH3CHOHCOOH: 20~34g / L, the solvent is water.

[0029] Preferably, in step S2, the pH value of the chemical plating solution is 5.0-6.5.

[0030] Preferably, in step S3, the hot dip coating process specifically comprises the following steps: S31, using a resistance furnace to melt and heat-insulate the aluminum material for hot-dip plating to obtain an aluminum melt, the heat-insulating temperature being 720-740° C.; S32, placing the iron substrate with the intermediate layer prepared on the surface into the aluminum melt and keeping it for 3 to 5 minutes; S33. Slowly (10-15s) remove the iron substrate from the aluminum melt and observe the coating state of the aluminum melt; if the surface coating is bright silver, the surface is smooth, and there is no leakage, it indicates that the hot-dip plating treatment is good; otherwise, the hot-dip plating treatment needs to be repeated.

[0031] Preferably, in step S3, the aluminum material is pure aluminum or aluminum alloy (such as aluminum silicon alloy such as ZL101A, ZL702A, aluminum copper alloy ZL205A, etc.). Further preferably, the aluminum material is hypoeutectic Al-Si alloy ZL702A, which has good fluidity and excellent performance. In terms of weight percentage, its composition is Si: 6.0~8.0wt%, Mg: 0.25~0.50wt%, Cu: 1.2~1.8wt%, Mn: 0.1~0.25wt%, Fe≤0.15wt%, and the balance is Al and unavoidable impurities.

[0032] Preferably, in step S4, the liquid-solid composite casting process specifically includes the following steps: S41, melting the aluminum material for casting in a resistance furnace to obtain an aluminum melt, and then performing rotary degassing; S42, adjust the temperature of the resistance furnace to 700-720°C, and let the aluminum melt stand for 5-10 minutes; S43, slagging the surface of the aluminum melt; S44. Place the hot-dip-plated iron substrate into the mold, and quickly (3 to 5 seconds) pour the molten aluminum in the resistance furnace into the mold to complete the aluminum / iron bimetallic liquid-solid composite casting.

[0033] Preferably, in step S4, the aluminum material is the same as the aluminum material for hot-dip plating.

[0034] According to another aspect of the present invention, the present invention provides the following technical solution: An aluminum / iron bimetallic composite material based on chemical nickel plating is prepared by adopting the preparation method of the aluminum / iron bimetallic composite material based on chemical nickel plating, wherein the middle layer is a nickel middle layer with a thickness of 14-18 μm.

[0035] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0036] Example 1 In this embodiment, the iron substrate is ductile iron QT500, and its composition is, by weight percentage, C: 3.7wt%, Si: 2.7wt%, Mn: 0.2wt%, S: 0.015wt%, P: 0.05wt%, Mg: 0.04wt%, RE: 0.04wt%, and the balance is Fe and inevitable impurities. The aluminum material is hypoeutectic Al-Si alloy ZL702A, and its composition is, by weight percentage, Si: 7.0wt%, Mg: 0.30wt%, Cu: 1.5wt%, Mn: 0.15wt%, Fe: 0.10wt%, and the balance is Al and inevitable impurities. The preparation method of aluminum / iron bimetallic composite material based on chemical nickel plating layer includes the following steps: S1. Surface treatment of the iron substrate; S11. Use an electric grinder or shot peening machine to grind or shot peen the surface of the iron substrate until there is no black or yellow oxide and impurities on the surface to remove rust; S12, placing the iron substrate in a 10.0wt% NaOH aqueous solution and ultrasonically cleaning it for 5 minutes to remove oil; S13, placing the iron substrate in anhydrous ethanol solution, ultrasonically cleaning for 5 minutes, and washing away the residual NaOH; S14, placing the iron substrate in a 10.0wt% HCl aqueous solution and ultrasonically cleaning it for 5 minutes for activation; S15, placing the iron substrate in anhydrous ethanol solution, and ultrasonically cleaning for 5 minutes to wash away the residual HCl; S16, drying the iron substrate.

[0037] S2, preparing an intermediate layer on the surface of the iron substrate by chemical plating; S21. Place the chemical plating solution in a container and place the container in a water bath; the composition of the chemical plating solution is as follows: NiSO4·6H2O: 30 g / L, NaH2PO2·H2O: 25 g / L, NaC2H3O2: 4 g / L, Na2CO3: 1.5 g / L, CH3CHOHCOOH: 28 g / L, and the solvent is water; the pH value of the chemical plating solution is 5.5.

[0038] S22, placing the surface treated iron substrate into a prepared chemical plating solution, and performing chemical plating at 90° C. for 10 min; S23, placing the electroless plated iron substrate in a 10wt% Na2CO3 solution and soaking it for 10 minutes for alkaline cleaning; S24, placing the iron substrate in anhydrous ethanol solution and ultrasonically cleaning for 10 minutes; S25, drying the iron substrate. A nickel intermediate layer is prepared on the surface of the iron substrate, and the thickness of the nickel intermediate layer is measured at four locations as shown in Table 1 below. It can be seen that the thickness of the nickel intermediate layer obtained by chemical plating is uniform.

[0039] Table 1 Nickel intermediate layer thickness S3, hot-dip plating treatment of an iron substrate with an intermediate layer prepared on the surface; S31, using a resistance furnace to melt and heat-insulate the aluminum material for hot-dip plating to obtain an aluminum melt, the heat-insulating temperature being 740° C.; S32, placing the iron substrate with the intermediate layer prepared on the surface into the aluminum melt and keeping it for 4 minutes; S33. Slowly (15s) remove the iron substrate from the aluminum melt and observe the coating state of the aluminum melt; the surface coating layer is bright silver, and the surface is smooth and there is no leakage, indicating that the hot-dip coating treatment effect is good; S4, using an aluminum solution and an iron substrate treated by hot-dip plating to perform liquid-solid composite casting to obtain an aluminum / iron bimetallic composite material based on a chemical nickel plating layer; S41, melting the aluminum material for casting in a resistance furnace to obtain an aluminum melt, and then performing rotary degassing; S42, adjusting the temperature of the resistance furnace to 720°C, and allowing the aluminum melt to stand for 8 minutes; S43, slagging the surface of the aluminum melt; S44. Place the hot-dip-plated iron substrate into the mold, and quickly (5s) pour the molten aluminum in the resistance furnace into the mold to complete the aluminum / iron bimetallic liquid-solid composite casting.

[0040] Scanning electron microscope photos of the metal interface of aluminum / iron bimetallic composites are shown in Figure 2. Figure 1 As shown in the figure, the left side is the iron substrate, the right side is the aluminum alloy, and the silver strip at the metal interface is the nickel intermediate layer. The thickness of the nickel intermediate layer is between 13 and 14 μm, which is due to the dissolution of part of the nickel layer after hot-dip plating. The thickness of the reaction layer is between 21 and 23 μm. The reaction layer generates many needle-like protrusions near the aluminum side, because the nickel element diffuses into ZL702A and reacts with the aluminum element to form a new metal compound, thus forming a needle-like interface layer.

[0041] Figure 2 The energy spectrum analysis result at the metal interface of the aluminum / iron bimetallic composite material of Example 1 of the present invention confirms that the position of point 1 ( Figure 1 The silver bright band in the middle is the nickel middle layer, and point 2 ( Figure 1 The needle-like protrusions on the aluminum side are Al3Ni phase. Brittle Al on the interface of aluminum / iron bimetallic composites 13 Fe4, Al5Fe2, and Al2Fe phases were not found. This means that the original brittle Al-Fe phase has completely disappeared.

[0042] Comparative Example 1 The difference from Embodiment 1 is that steps S2-S3 are not performed.

[0043] Comparative Example 2 The difference from Example 1 is that step S2 adopts an electroplating process to prepare the intermediate layer: the plating solution is placed in a beaker, and the beaker is placed in a water bath; a nickel rod with a purity of 99.9% is hung on the anode and inserted into the electrodeposition solution at a fixed position; the surface-treated iron substrate is hung on the cathode and also inserted into the electrodeposition solution at a fixed position; after the water bath temperature reaches 30-40°C, the electroplating power supply is turned on, and the current density is 1A / dm 2 The electroplating time is 10 to 20 minutes; the plating solution ratio of the electroplated nickel layer is as follows: NiSO4•7H2O: 135g / L, H3BO3: 18g / L, NaSO4: 75g / L, C 12 H 25 SO4Na: 5g / L, HCl: 0.18mL / L. In addition, the pH value of the plating solution must be maintained at 3.5.

[0044] The shear strength of the aluminum / iron bimetallic composite material of Comparative Example 1 is only 9.32MPa, which means that the aluminum / iron bimetallic composite material under traditional liquid-solid composite casting can only achieve mechanical bite, and a good reaction layer is not formed at the interface. However, when the chemical plating and hot-dip plating processes of the present invention are added to the treatment of the aluminum / iron bimetallic interface, the shear strength of the aluminum / iron bimetallic composite material of Example 1 is as high as 46.46MPa, which is nearly 4 times higher than that of Comparative Example 1. This result shows that the chemical nickel plating layer effectively blocks the element diffusion between aluminum and iron, and this method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer can greatly strengthen the interface. It breaks the shackles of the aluminum / iron bimetallic interface being easy to crack under traditional liquid-solid composite casting.

[0045] Comparative Example 2: A nickel intermediate layer was prepared on the surface of an iron substrate. The thickness of the nickel intermediate layer was measured at four locations as shown in Table 2. It can be seen that the thickness of the nickel intermediate layer obtained by electroplating is uneven.

[0046] Table 2 Nickel intermediate layer thickness The shear strength of the aluminum / iron bimetallic composite material of Comparative Example 2 is 29.83 MPa. The uneven nickel intermediate layer leads to inconsistent stress distribution at the aluminum / iron bimetallic interface. The locations where the nickel intermediate layer is too thin or too thick become crack initiation points, destroying the shear strength of the aluminum / iron bimetallic material.

[0047] It can be seen from the above embodiments and comparative examples that the present invention pre-disposes a nickel layer of uniform thickness on the surface of the iron substrate by chemical plating, which has the effect of completely isolating the direct contact between the aluminum melt and the solid iron substrate. The present invention can achieve the control of the interface phase composition of the aluminum / iron bimetallic composite material, greatly reduce interface defects, and improve the interface bonding strength.

[0048] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive 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 method for preparing an aluminum / iron bimetallic composite material based on a chemical nickel plating layer, characterized in that: The steps include: S1. Surface treatment of the iron substrate; S2, preparing an intermediate layer on the surface of the iron substrate by chemical plating; S3, hot-dip plating treatment of an iron substrate with an intermediate layer prepared on the surface; S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate after hot-dip plating to obtain an aluminum / iron bimetallic composite material based on a chemical nickel plating layer.

2. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In the step S1, the surface treatment includes degreasing, rust removal, and activation treatment.

3. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In the step S1, the iron base material includes iron and steel.

4. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In step S2, the chemical plating process specifically includes the following steps: S21, placing the chemical plating solution in a container, and placing the container in a water bath; S22, placing the surface treated iron substrate into a prepared chemical plating solution for chemical plating; S23, immersing the chemically plated iron substrate in a Na2CO3 solution for alkaline cleaning; S24, placing the iron substrate in an anhydrous ethanol solution for ultrasonic cleaning; S25, drying the iron substrate.

5. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 4, characterized in that: In step S2, the composition of the chemical plating solution is as follows: NiSO4·6H2O: 21~35g / L, NaH2PO2·H2O: 16~30g / L, NaC2H3O2: 2~6g / L, Na2CO3: 1~2.2g / L, CH3CHOHCOOH: 20~34g / L, the solvent is water.

6. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 4, characterized in that: In step S2, the pH value of the chemical plating solution is 5.0-6.

5.

7. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In step S3, the hot dip coating process specifically includes the following steps: S31, melting and heat-insulating the aluminum material for hot-dip coating to obtain an aluminum melt; S32, placing the iron substrate with the intermediate layer prepared on the surface into the aluminum melt; S33. Take out the iron substrate from the aluminum melt and observe the coating state of the aluminum melt; if the surface coating layer is silvery bright, the surface is smooth, and there is no leakage, it indicates that the hot dip coating treatment effect is good; Otherwise, hot dip galvanizing is performed again.

8. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In step S3, the aluminum material is pure aluminum or aluminum alloy.

9. The method for preparing the aluminum / iron bimetallic composite material based on chemical nickel plating layer according to claim 1, characterized in that: In step S4, the liquid-solid composite casting process specifically includes the following steps: S41, melting the aluminum material for casting to obtain an aluminum melt, and then performing rotation degassing; S42, allowing the aluminum melt to stand still; S43, slagging the surface of the aluminum melt; S44, placing the hot-dip-plated iron substrate into a mold, pouring the molten aluminum into the mold, and completing the aluminum / iron bimetallic liquid-solid composite casting.

10. An aluminum / iron bimetallic composite material based on chemical nickel plating, characterized in that: The aluminum / iron bimetallic composite material is prepared by the preparation method based on chemical nickel plating layer according to any one of claims 1 to 9, wherein the middle layer is a nickel middle layer and its thickness is 14 to 18 μm.

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