Insulator iron cap and preparation method thereof

Abstract

The invention relates to the technical field of insulator iron cap production, in particular to an insulator iron cap and a preparation method thereof.The preparation method comprises the steps that after a steel ladle is preheated, a part of spheroidizing agent and a part of nucleating agent are laid at the bottom of the steel ladle, and a TiC-SiC-Fe reinforcing material plate is laid at the top of the spheroidizing agent and the top of the nucleating agent; the remaining spheroidizing agent and nucleating agent are subjected to core wrapping with aluminum, and an aluminum core-spun yarn is obtained; the molten iron liquid is injected into a steel ladle, dross is skimmed after a reaction, then an aluminum core-spun yarn is fed into the steel ladle, the reaction is continued, dross is skimmed again after the reaction is finished, and enhanced molten iron is obtained; pouring enhanced molten iron into the mold, and carrying out solidification, cooling, demolding and fine finishing to obtain an intermediate casting; and carrying out hot-dip galvanizing treatment on the intermediate casting, and plating a corrosion-resistant zinc layer to obtain the insulator iron cap. The TiC-SiC-Fe reinforced material plate is used for refining grains, the nodulizing agent and the nucleating agent are added in batches, and the corrosion-resistant zinc layer is plated, so that the prepared insulator iron cap has excellent mechanical strength and corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of insulator iron cap production, in particular to an insulator iron cap and a preparation method thereof. Background Art

[0002] Insulator caps are important insulating materials in power systems, mainly used to protect insulators from the influence of the external environment. Generally, insulator caps install insulators inside them to ensure the safety and stability of insulators. The material of insulator caps is an important factor in determining their service life and safety. Insulator caps are mostly made of ductile iron, which is a type of cast iron based on spherical graphite. It has good performance and is suitable for manufacturing large machine parts and important industrial components. However, for some harsh application scenarios, insulator caps made of ductile iron are difficult to meet the application requirements because their mechanical properties and corrosion resistance cannot keep up with the use requirements. Based on this, an insulator cap and a preparation method thereof are proposed. Summary of the invention

[0003] In order to address the deficiencies in the prior art, the present invention provides an insulator cap and a preparation method thereof, so that the prepared insulator cap has excellent mechanical strength and corrosion resistance, thereby increasing the service life of the insulator cap and meeting the complex application scenarios of the insulator cap.

[0004] To achieve the above object, the present invention provides the following technical solution: an insulator cap and a preparation method thereof, comprising the following steps:

[0005] (1) After the ladle is preheated, part of the spheroidizer and inoculant are laid flat on the bottom, and a TiC-SiC-Fe reinforcing plate is laid on top of the spheroidizer and inoculant;

[0006] (2) core-coating the remaining spheroidizing agent and inoculant with aluminum to obtain an aluminum core-coated wire;

[0007] (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid;

[0008] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0009] (5) The intermediate casting is subjected to hot-dip galvanizing treatment and plated with a corrosion-resistant zinc layer to obtain an insulator iron cap.

[0010] Preferably, the TiC-SiC-Fe reinforcing plate accounts for 0.1-0.15% of the mass of the molten iron; the spheroidizer accounts for 0.8-1.2% of the mass of the molten iron; and the inoculant accounts for 0.2-0.3% of the mass of the molten iron.

[0011] Preferably, in terms of mass percentage, the spheroidizer comprises Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant comprises Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0012] Preferably, the TiC-SiC-Fe reinforced material plate is prepared as follows: S1, nano-TiC, SiC powder and Fe powder are sent to a ball mill for ball milling, and a mixed powder is obtained by screening; S2, the temperature of the mixed powder is increased to 800-850°C, and it is pressed into a sheet shape under an inert atmosphere to obtain a TiC-SiC-Fe reinforced material plate.

[0013] Preferably, in step S1, the mass ratio of the Fe powder, nano-TiC and SiC powder is 3:2:3.

[0014] Preferably, in step S1, the SiC powder is composed of various particle sizes, of which the particle sizes less than 1 μm account for 30-35%; the particle sizes between 1-2 μm account for 35-40%; and the particle sizes greater than 2 μm account for 30-35%.

[0015] Preferably, in step (3), the molten iron comprises, by mass percentage, 3.5-4.0% C, 2.2-3.2% Si, 0.2-0.8% Mn, 0.03-0.04% Mg, ≤0.05% S, ≤0.05% P, and the balance is Fe.

[0016] Preferably, in step (5), the hot-dip galvanizing treatment is as follows: after the intermediate casting is cleaned and assisted in plating, it is placed in alloy liquid, and a corrosion-resistant zinc layer is plated at 450-460° C., and then taken out and cooled and passivated.

[0017] Preferably, in terms of mass percentage, the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance is Zn.

[0018] The present invention also provides an insulator cap obtained by the above-mentioned preparation method, wherein the insulator cap consists of an intermediate casting and a corrosion-resistant zinc layer.

[0019] The present invention provides an insulator cap and a preparation method thereof, which has the following advantages compared with the prior art:

[0020] Beneficial effects:

[0021] The present invention uses TiC-SiC-Fe reinforcing material plates to refine grains, adds spheroidizing agent and inoculant in batches in the form of paving the bottom of the ladle and aluminum cored wire, and adopts hot-dip galvanizing to plate a corrosion-resistant zinc layer, so that the prepared insulator cap has excellent mechanical strength and corrosion resistance, improves the service life of the insulator cap, and meets the complex application scenarios of the insulator cap. Specifically, TiC-SiC particles can be used as heterogeneous nucleation cores of graphite balls and austenite, increasing the number of nucleations of graphite balls and austenite per unit area, and the TiC-SiC particles distributed at the solid-liquid interface hinder the movement of the liquid-solid interface to a certain extent, delay the growth of primary grains, thereby achieving the refinement of the matrix organization grains.

[0022] The present invention uses a mixture of SiC particles of various particle sizes. Particles smaller than 1 micron can provide nucleation cores or promote non-uniform nucleation. Particles between 1-2 microns are distributed in the matrix as second phase particles. Particles larger than 2 microns enter the molten metal to inhibit crystal growth, thereby improving the overall quality of the insulator cap.

[0023] The invention preliminarily ball-mills nano-TiC, SiC powder and iron powder to make the three powders evenly mixed, and then presses the mixture at high temperature, so that the nano-TiC and SiC powders can be evenly embedded in the iron powder particles, and the problems of agglomeration and floating of the nano-TiC and SiC powders in molten iron can be solved, and the nano-TiC and SiC powders can be evenly distributed in the molten iron, which is helpful to improve the quality of the insulator iron cap. DETAILED DESCRIPTION

[0024] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0025] Example 1

[0026] The preparation of TiC-SiC-Fe reinforced sheet is as follows:

[0027] S1. Nano-TiC, SiC powder and Fe powder are fed into a ball mill in a mass ratio of 2:3:3 for ball milling, and then sieved to obtain a mixed powder; wherein the SiC powder is composed of various particle sizes, of which the particle size is less than 1 μm accounts for 30%; the particle size is between 1-2 μm accounts for 40%; and the particle size is greater than 2 μm accounts for 30%.

[0028] S2. Raise the temperature of the mixed powder to 800°C and press it into a sheet under an inert atmosphere (nitrogen) to obtain a TiC-SiC-Fe reinforced plate.

[0029] Example 2

[0030] The preparation of TiC-SiC-Fe reinforced sheet is as follows:

[0031] S1. Nano-TiC, SiC powder and Fe powder are fed into a ball mill in a mass ratio of 2:3:3 for ball milling, and then sieved to obtain a mixed powder; wherein the SiC powder is composed of various particle sizes, of which the particle size is less than 1 μm accounting for 35%; the particle size is between 1-2 μm accounting for 35%; and the particle size is greater than 2 μm accounting for 30%.

[0032] S2. Raise the temperature of the mixed powder to 820°C and press it into a sheet under an inert atmosphere (nitrogen) to obtain a TiC-SiC-Fe reinforced plate.

[0033] Example 3

[0034] The preparation of TiC-SiC-Fe reinforced sheet is as follows:

[0035] S1. Nano-TiC, SiC powder and Fe powder are fed into a ball mill in a mass ratio of 2:3:3 for ball milling, and then sieved to obtain a mixed powder; wherein the SiC powder is composed of various particle sizes, of which the particle size is less than 1 μm accounts for 30%; the particle size is between 1-2 μm accounts for 35%; and the particle size is greater than 2 μm accounts for 35%.

[0036] S2. Raise the temperature of the mixed powder to 850°C and press it into a sheet under an inert atmosphere (nitrogen) to obtain a TiC-SiC-Fe reinforced plate.

[0037] Example 4

[0038] A method for preparing an insulator cap comprises the following steps:

[0039] (1) After the ladle is preheated, 50 wt% of spheroidizer and inoculant are spread on the bottom of the ladle, and a TiC-SiC-Fe reinforcing plate (prepared in Example 1) is laid on top of the spheroidizer and inoculant;

[0040] In terms of mass percentage, the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0041] (2) The remaining 50 wt% of the spheroidizing agent and the inoculant are coated with aluminum to obtain an aluminum cored wire.

[0042] (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid;

[0043] In terms of mass percentage, the molten iron includes C 4.0%, Si 2.2%, Mn 0.8%, Mg 0.03%, S≤0.05%, P≤0.05%, and the balance is Fe;

[0044] The TiC-SiC-Fe reinforcing plate accounts for 0.15% of the mass of the molten iron; the spheroidizer accounts for 0.8% of the mass of the molten iron; and the inoculant accounts for 0.3% of the mass of the molten iron.

[0045] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0046] (5) After cleaning and assisting plating, the intermediate casting is sent into an alloy liquid (calculated by mass percentage, the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance is Zn). A corrosion-resistant zinc layer with a thickness of 85 μm is plated at 450°C. After being taken out, it is cooled and passivated to obtain an insulator iron cap.

[0047] Example 5

[0048] A method for preparing an insulator cap comprises the following steps:

[0049] (1) After the ladle is preheated, 40 wt% of spheroidizer and inoculant are spread on the bottom of the ladle, and a TiC-SiC-Fe reinforcing plate (prepared in Example 2) is laid on top of the spheroidizer and inoculant;

[0050] In terms of mass percentage, the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0051] (2) The remaining 60 wt% of the spheroidizing agent and the inoculant are coated with aluminum to obtain an aluminum cored wire.

[0052] (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid;

[0053] In terms of mass percentage, the molten iron includes C 3.5%, Si 3.2%, Mn 0.2%, Mg 0.04%, S≤0.05%, P≤0.05%, and the balance is Fe;

[0054] The TiC-SiC-Fe reinforcing plate accounts for 0.1% of the mass of the molten iron; the spheroidizer accounts for 1.2% of the mass of the molten iron; and the inoculant accounts for 0.2% of the mass of the molten iron.

[0055] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0056] (5) After cleaning and assisting plating, the intermediate casting is sent into an alloy liquid (calculated by mass percentage, the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance is Zn). A corrosion-resistant zinc layer with a thickness of 110 μm is plated at 460°C. After being taken out, it is cooled and passivated to obtain an insulator iron cap.

[0057] Example 6

[0058] A method for preparing an insulator cap comprises the following steps:

[0059] (1) After the ladle is preheated, 70 wt% of spheroidizer and inoculant are spread on the bottom of the ladle, and a TiC-SiC-Fe reinforcing plate (prepared in Example 3) is laid on top of the spheroidizer and inoculant;

[0060] In terms of mass percentage, the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0061] (2) The remaining 30 wt% of the spheroidizing agent and the inoculant are coated with aluminum to obtain an aluminum cored wire.

[0062] (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid;

[0063] In terms of mass percentage, the molten iron includes 3.8% C, 2.6% Si, 0.5% Mn, 0.035% Mg, ≤0.05% S, ≤0.05% P, and the balance is Fe;

[0064] The TiC-SiC-Fe reinforcing plate accounts for 0.12% of the mass of the molten iron; the spheroidizer accounts for 1.0% of the mass of the molten iron; and the inoculant accounts for 0.25% of the mass of the molten iron.

[0065] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0066] (5) After cleaning and plating, the intermediate casting is placed in an alloy liquid (the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance Zn, in terms of mass percentage), and a corrosion-resistant zinc layer with a thickness of 135 μm is plated at 455° C. After being taken out, it is cooled and passivated to obtain an insulator cap.

[0067] Comparative Example 1

[0068] A method for preparing an insulator cap comprises the following steps:

[0069] (1) After the ladle is preheated, 70wt% of spheroidizer and inoculant are spread on the bottom of the ladle;

[0070] In terms of mass percentage, the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0071] (2) The remaining 30 wt% of the spheroidizing agent and the inoculant are coated with aluminum to obtain an aluminum cored wire.

[0072] (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid;

[0073] In terms of mass percentage, the molten iron includes 3.8% C, 2.6% Si, 0.5% Mn, 0.035% Mg, ≤0.05% S, ≤0.05% P, and the balance is Fe;

[0074] The spheroidizer accounts for 1.0% of the mass of the molten iron; the inoculant accounts for 0.25% of the mass of the molten iron.

[0075] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0076] (5) After cleaning and plating, the intermediate casting is placed in an alloy liquid (the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance Zn, in terms of mass percentage), and a corrosion-resistant zinc layer with a thickness of 135 μm is plated at 455° C. After being taken out, it is cooled and passivated to obtain an insulator cap.

[0077] Comparative Example 2

[0078] The same as Example 6, except that the TiC-SiC-Fe reinforced sheet is prepared as follows:

[0079] S1. Nano-TiC, SiC powder and Fe powder are fed into a ball mill in a mass ratio of 2:3:3 for ball milling, and then sieved to obtain a mixed powder; wherein the SiC powder is composed of various particle sizes, of which the particle size is less than 1 μm accounts for 30%; the particle size is between 1-2 μm accounts for 35%; and the particle size is greater than 2 μm accounts for 35%.

[0080] S2. In an inert atmosphere (nitrogen), cold pressing is performed to form a sheet to obtain a TiC-SiC-Fe reinforced plate.

[0081] Comparative Example 3

[0082] The same as Example 6, except that the TiC-SiC-Fe reinforced sheet is prepared as follows:

[0083] S1. Nano-TiC, SiC powder and Fe powder are fed into a ball mill in a mass ratio of 2:3:3 for ball milling, and then sieved to obtain a mixed powder; wherein the particle size of SiC powder is uniformly 1 μm.

[0084] S2. Raise the temperature of the mixed powder to 850°C and press it into a sheet under an inert atmosphere (nitrogen) to obtain a TiC-SiC-Fe reinforced plate.

[0085] Comparative Example 4

[0086] A method for preparing an insulator cap comprises the following steps:

[0087] (1) After the ladle is preheated, a spheroidizer and an inoculant are laid flat on the bottom of the ladle, and a TiC-SiC-Fe reinforcing material plate (prepared in Example 3) is laid on top of the spheroidizer and the inoculant;

[0088] In terms of mass percentage, the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe; the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

[0089] (2) injecting molten iron into a ladle, and skimming off slag after reaction to obtain enhanced iron liquid;

[0090] In terms of mass percentage, the molten iron includes 3.8% C, 2.6% Si, 0.5% Mn, 0.035% Mg, ≤0.05% S, ≤0.05% P, and the balance is Fe;

[0091] The TiC-SiC-Fe reinforcing plate accounts for 0.12% of the mass of the molten iron; the spheroidizer accounts for 1.0% of the mass of the molten iron; and the inoculant accounts for 0.25% of the mass of the molten iron.

[0092] (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing;

[0093] (5) After cleaning and plating, the intermediate casting is placed in an alloy liquid (the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance Zn, in terms of mass percentage), and a corrosion-resistant zinc layer with a thickness of 135 μm is plated at 455° C. After being taken out, it is cooled and passivated to obtain an insulator cap.

[0094] Comparative Example 5

[0095] A method for preparing an insulator cap comprises the following steps:

[0096] Steps (1) to (4) are the same as those in Example 6, except that:

[0097] (5) After cleaning and assisting plating, the intermediate casting is sent into an alloy liquid (calculated by mass percentage, the alloy liquid includes 0.7% Al and the balance is Zn). A corrosion-resistant zinc layer with a thickness of 135 μm is plated at 455°C. After being taken out, it is cooled and passivated to obtain an insulator iron cap.

[0098] Quality Inspection

[0099] 1. The methods for preparing intermediate castings in Examples 4-6 and Comparative Examples 1-4 were used to prepare test pieces that met the standards, and the mechanical properties of each test piece were tested with reference to GB / T1348-2009 and the standards cited therein. The specific results are shown in the following table.

[0100] Table 1 Mechanical properties

[0101] category Tensile strength(MPa) Yield strength(MPa) <![CDATA[Toughness (J / cm 2 )]]> Example 4 652 454 68 Example 5 661 470 72 Example 6 675 487 83 Comparative Example 1 482 349 58 Comparative Example 2 604 413 62 Comparative Example 3 626 441 65 Comparative Example 4 633 449 66

[0102] From the above table, we can see that:

[0103] (1) Compared with Example 6, the strength of the specimen in Comparative Example 1 decreased significantly, indicating that the addition of the TiC-SiC-Fe reinforcing plate can indeed significantly improve the mechanical properties of the specimen.

[0104] (2) Compared with Example 6, the strength of the specimen in Comparative Example 1 is slightly reduced, indicating that the high-temperature hot pressing plate, the mixing of SiC powders with various particle sizes, and the batch use of spheroidizing agent and inoculant can improve the mechanical properties of the specimen.

[0105] 2. Performing neutral salt spray corrosion test and appearance rating test on the insulator caps in Example 6, Comparative Example 1 and Comparative Example 5;

[0106] Neutral salt spray corrosion test: refer to GB / T 10125-1997, immerse the plated parts in sodium chloride solution, observe the area of ​​"white rust" on the plated parts after a certain period of time, and calculate the percentage of "white rust" area by cross-cutting method;

[0107] Appearance rating test: Refer to GB / T 10125-1997, use continuous spray test for a certain period of time, observe the area of ​​"white rust", and refer to the standards in GB / T 6461-2002 to grade the plated parts after the test. The rating from good to bad is 10-0. The specific results are shown in the following table.

[0108] Table 2 Corrosion resistance

[0109]

[0110]

[0111] It can be seen from the above table that the insulator cap prepared in Example 6 has excellent corrosion resistance, while the corrosion resistance of Comparative Examples 1 and 5 is reduced, indicating that the TiC-SiC-Fe reinforced plate can improve the corrosion resistance of the intermediate casting; adding Mn to the zinc liquid can improve the uniformity of the coating, thereby improving the corrosion resistance of the coating.

[0112] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an insulator cap, characterized in that: The following steps are involved: (1) After the ladle is preheated, part of the spheroidizer and inoculant are laid flat on the bottom, and a TiC-SiC-Fe reinforcing plate is laid on top of the spheroidizer and inoculant; (2) core-coating the remaining spheroidizing agent and inoculant with aluminum to obtain an aluminum core-coated wire; (3) injecting the molten iron into a ladle, skimming off the scum after the reaction, then feeding an aluminum cored wire into the ladle and continuing the reaction, and skimming off the scum again after the reaction is completed to obtain enhanced iron liquid; (4) pouring the enhanced molten iron into the mold, and obtaining an intermediate casting after solidification, cooling, demoulding, and fine finishing; (5) The intermediate casting is subjected to hot-dip galvanizing treatment and plated with a corrosion-resistant zinc layer to obtain an insulator iron cap.

2. The method for preparing an insulator cap according to claim 1, characterized in that: In step (1), the TiC-SiC-Fe reinforcing plate accounts for 0.1-0.15% of the mass of the molten iron; the spheroidizer accounts for 0.8-1.2% of the mass of the molten iron; and the inoculant accounts for 0.2-0.3% of the mass of the molten iron.

3. The method for preparing an insulator cap according to claim 1, characterized in that: In step (1), the spheroidizer includes Si 42%, Mg 8%, Ce 7%, Ca 2%, and the balance is Fe, and the inoculant includes Si 75%, C 0.2%, Al 1.2%, Ca 0.8%, and the balance is Fe.

4. The method for preparing an insulator cap according to claim 1, characterized in that: In step (1), the TiC-SiC-Fe reinforced material plate is prepared as follows: S1, sending nano-TiC, SiC powder and Fe powder into a ball mill for ball milling, and obtaining a mixed powder after sieving; S2. Raise the temperature of the mixed powder to 800-850°C and press it into a sheet under an inert atmosphere to obtain a TiC-SiC-Fe reinforced plate.

5. The method for preparing an insulator cap according to claim 4, characterized in that: In step S1, the mass ratio of the Fe powder, nano-TiC and SiC powder is 3:2:

3.

6. The method for preparing an insulator cap according to claim 4, characterized in that: In step S1, the SiC powder is composed of various particle sizes, of which the particle size is less than 1 μm accounting for 30-35%; the particle size is between 1-2 μm accounting for 35-40%; and the particle size is greater than 2 μm accounting for 30-35%.

7. The method for preparing an insulator cap according to claim 1, characterized in that: In step (3), the molten iron comprises, by mass percentage, 3.5-4.0% C, 2.2-3.2% Si, 0.2-0.8% Mn, 0.03-0.04% Mg, ≤0.05% S, ≤0.05% P, and the balance is Fe.

8. The method for preparing an insulator cap according to claim 1, characterized in that: In step (5), the hot-dip galvanizing treatment is as follows: after the intermediate casting is cleaned and assisted in plating, it is sent into the alloy liquid, and a corrosion-resistant zinc layer is plated at 450-460° C., and then it is taken out and cooled and passivated.

9. The method for preparing an insulator cap according to claim 8, characterized in that: In terms of mass percentage, the alloy liquid includes 0.7% Al, 0.15% Mn, and the balance is Zn.

10. An insulator cap obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The insulator cap is composed of an intermediate casting and a corrosion-resistant zinc layer.

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