Low-adhesion long-life crust breaking hammer head based on cathode scrap steel reinforcement and preparation method of low-adhesion long-life crust breaking hammer head

Abstract

The invention provides a low-adhesion long-life crust breaking hammer based on cathode scrap steel reinforcement and a preparation method thereof, and belongs to the technical field of aluminum electrolysis. The preparation method comprises the following steps: taking cathode scrap steel generated by electrolytic aluminum overhaul as a main raw material, adding chromium, nickel, boron, silicon iron and lanthanide rare earth metal, and smelting to prepare an alloy melt; a pre-coating layer is formed on the surface of a preheated crust breaking hammer base body through a dip plating process, then hot extrusion is conducted through a special mold, and a compact and shaped reinforced protection layer which is in metallurgical bonding with the base body is obtained at a time. According to the prepared crust breaking hammer head, the protective layer generates a carbide hard phase in situ by utilizing carbon in cathode waste steel, and the crust breaking hammer head has high hardness and extremely low electrolyte molten salt adhesion and is high in bonding strength and good in impact resistance. According to the method, high-value utilization of the cathode scrap steel is achieved, the process is simple and efficient, the service life of the obtained product under the complex working conditions of electrolytic aluminum high temperature, corrosion and impact is remarkably prolonged, and the important economic and environment-friendly value is achieved.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling and metal surface strengthening technology, specifically relating to a low-adhesion, long-life shell-breaking hammer head and its preparation method based on the high-value utilization of scrap steel from electrolytic aluminum solid waste cathodes. Background Technology

[0002] Shell-breaking hammers are widely used in the electrolytic aluminum industry. They are mainly made of Q235 low-carbon steel. However, the working conditions in electrolytic aluminum production are quite complex. High temperature, aluminum liquid corrosion, electrolyte corrosion, and oxidizing atmosphere can severely damage the Q235 matrix. In addition, since some components in the electrolytic cell may have high hardness, the shell-breaking hammers are subject to severe wear. The end result is that the shell-breaking hammers are worn out due to excessive wear and lose their function. Furthermore, Fe in the Q235 matrix may seep into the aluminum liquid, causing contamination and reducing product purity.

[0003] In existing technologies, common methods for solving the wear problem of shell-breaking hammerheads mainly involve covering the surface of the hammerhead with a protective layer or doping the matrix material of the hammerhead with reinforcing elements. For example, in patent CN 108796387 A, W is incorporated into the matrix material as the main reinforcing element, along with Ni, Cr, Mn, and other elements for further strengthening. The AOD smelting method or the KAWASAKI-BOP smelting method is used for smelting, followed by heat treatment and forging. The problem is that the incorporation of W increases costs, and the AOD smelting method requires argon gas, but the preparation cost of rare gases is high, leading to increased costs. Furthermore, this method also incorporates harmful elements such as N and S, which is detrimental to improving product purity, and the entire process is time-consuming. Among existing solutions involving protective coatings, one method is to infiltrate TiC onto the surface of the hammerhead using a dual-glow plasma infiltration process. Although the infiltrated TiC hard phase can improve the surface hardness of the hammerhead, Ti is expensive, and dual-glow plasma infiltration is time-consuming and complex, making it unsuitable for large-scale industrial production. There is also a technology that uses an alloy material layer, a diffusion layer and a ceramic material layer to metallurgically bond together to prepare a shell-breaking hammerhead. However, the problem is that the alloy material matrix needs to add Ti and Mn. Ti is not easy to obtain, which increases the cost. At the same time, the diffusion layer needs to add the precious metal Ag, which further increases the cost. In addition, the metallurgical bonding strength between the ceramic phase and the metal phase is limited and cannot withstand too large an impact load, which prevents it from being used on a large scale in industrial production.

[0004] At the same time, the cathode scrap steel generated during the overhaul cycle of the electrolytic aluminum industry has a high surface carbon content due to long-term carburization, resulting in a low reuse rate, causing a lot of waste, affecting the economic benefits of enterprises, and also polluting the environment, which is not conducive to the long-term development of the industry.

[0005] Existing technologies, whether matrix alloying or surface protective coating, focus on improving material hardness and wear resistance, but generally overlook an equally critical factor leading to hammer failure in actual working conditions: severe adhesion and solidification of molten electrolyte on the hammer surface. Adhering electrolytes not only alter the hammer's morphology and affect hammering accuracy, but also create continuous chemical corrosion and thermal stress sources, accelerating coating peeling and failure. Some existing solutions propose using non-metallic materials to fundamentally solve the adhesion problem, but this introduces new engineering challenges such as high material costs, poor reliability of the metal / non-metal interface, and insufficient overall impact load resistance.

[0006] Therefore, developing a long-life tapping hammer that can effectively resist wear and electrolyte adhesion while balancing cost and performance, and achieving high-value utilization of solid waste (cathode scrap steel) from the electrolytic aluminum industry, thereby improving equipment reliability while realizing resource utilization of waste and reducing production costs, has become a comprehensive technical challenge that urgently needs to be overcome in this field. Based on this, this paper provides a method for preparing a tapping hammer that features low raw material costs, a simple and efficient process, a strong coating adhesion, and excellent wear resistance and anti-electrolyte adhesion properties. This method is of significant practical importance for promoting cost reduction, efficiency improvement, energy conservation, environmental protection, and sustainable development in the electrolytic aluminum industry. Summary of the Invention

[0007] One of the objectives of this invention is to provide a method for preparing a low-adhesion, long-life shell-breaking hammer head based on cathode scrap steel reinforcement. This method achieves the resource utilization of solid waste while preparing a metallurgical bonded coating on the surface of the shell-breaking hammer head that combines excellent wear resistance with extremely low electrolyte adhesion.

[0008] The second objective of this invention is to provide a shell-breaking hammerhead prepared by the above-described method. The reinforced coating on the working surface of the hammerhead is metallurgically bonded to the substrate, and its interior contains an in-situ synthesized hard carbide phase derived from the carbon source of cathode scrap steel. The surface exhibits low electrolyte adhesion characteristics, thus providing an exceptionally long service life under the complex conditions of high temperature, corrosion, and impact during aluminum electrolysis.

[0009] One of the technical solutions adopted by this invention to achieve its objective is: to provide a method for preparing a low-adhesion, long-life shell-breaking hammer head based on cathode scrap steel reinforcement, comprising the following steps: S1. By weight, 75-85 parts of cathode scrap steel with a carbon content of 1 wt%-2 wt% are mixed with 6-10 parts of chromium, 6-10 parts of nickel, 1-1.5 parts of ferrosilicon, 0.8-1 parts of boron and 0.7-1 parts of lanthanide rare earth metals, and smelted at 1400-1550℃. After the above raw materials are melted evenly, the surface slag is removed to obtain the alloy melt. S2. Immerse the shell-breaking hammer head into the alloy melt, rotate it several times, and then remove it. S3. Immediately place the removed shell-breaking hammer into the preheated extrusion molding die and extrude it for 10-20 seconds under a pressure of 200-300MPa. S4. Cool the extruded shell-beating hammer head to room temperature and then perform post-processing to obtain a shell-beating hammer head covered with a reinforced coating.

[0010] The overall concept and inventive principle of this invention are as follows: The preparation method provided by this invention uses cathode scrap steel generated from the overhaul of electrolytic aluminum as the main raw material. Through a short process of smelting-immersion plating-hot extrusion, it solves the problem of resource utilization of solid waste (cathode scrap steel) and prepares a metallurgical bonded coating on the surface of the shell-breaking hammer head that has both excellent wear resistance and extremely low electrolyte adhesion.

[0011] Based on long-term research in the electrolytic aluminum industry, the inventors discovered that the cathode scrap steel generated during major overhauls in the industry has a relatively high carbon content due to long-term carburization. Using this scrap steel as the main raw material, along with other components, and applying it to the surface of a shell-breaking hammerhead using a specific process to prepare a reinforced protective layer exhibits extremely low adhesion to molten electrolyte salts. The reasons for this are twofold: firstly, the high carbon content in the coating, coupled with its extremely dense structure after hot extrusion, creates a low surface energy, significantly reducing the wettability of the molten electrolyte salt; secondly, the carbide phase generated in situ by the high-temperature alloy melt under extrusion bonds well with the matrix, forming a uniform and stable microstructure, reducing the retention points of the molten salt. The synergistic effect of these factors significantly reduces the electrolyte coverage on the coating surface, fundamentally blocking the path of continuous corrosion. Combined with the coating's high wear resistance, this effectively extends the service life of the shell-breaking hammerhead.

[0012] Furthermore, the aforementioned preparation method directly incorporates alloying elements such as Cr and Ni into the cathode scrap steel and impregnates it onto the surface of the shell-breaking hammerhead in a molten state, followed by extrusion molding using a special mold. The advantage of this method is that it eliminates the need to grind raw materials into powder or wire for further cladding, significantly reducing coating manufacturing costs. Cr and Ni, among other metals, have high hardness, which enhances the strength and hardness of the shell-breaking hammerhead to some extent, thus extending its service life. The addition of lanthanide rare earth metals refines the grain size of the protective layer, improving its strength. More importantly, the main component, the cathode scrap steel, has a high carbon content, which can readily combine with the added alloying elements to form Cr... 23 Compounds such as C6, Cr7C3, and Cr3C2 enhance coating performance, making the hammerhead harder and more wear-resistant. Furthermore, die extrusion directly shapes the coating, allowing for one-step control of coating thickness and improved surface quality. This invention's preparation method, while producing high-quality coatings, reduces steps compared to conventional coating preparation methods, increasing production efficiency and improving enterprise economic benefits.

[0013] Further, in step S1, the cathode scrap steel is selected from cathode steel bars with a service life of 4-5 years, which are replaced during the regular overhaul of electrolytic cells in the aluminum electrolysis industry. Electrolytic cell cathode steel bars are conductive steel bars that connect to the cathode carbon blocks. After long-term service, carbides, electrolytes, and aluminum adhere to their surfaces, and they are replaced during the regular overhaul of the electrolytic cell. Typically, each small-to-medium-sized electrolytic cell (200-300 kA) produces approximately 40-60 cathode scrap steel bars, while ultra-large electrolytic cells (400-500 kA and above) produce approximately 70-100 cathode scrap steel bars. These cathode scrap steel bars, as industrial solid waste, are subject to high costs and low utilization rates with conventional treatment methods. This invention creatively transforms this industrial solid waste into a core raw material for reinforced coatings, achieving not only efficient resource recycling and cost reduction but, more importantly, cleverly utilizing its high carbon content (1 wt%-2 wt%) formed by long-term high-temperature carburizing, which reacts synergistically with added alloying elements to form a more wear-resistant and anti-adhesion reinforcing phase, ultimately achieving superior comprehensive performance that is difficult to achieve even with entirely new pure raw materials.

[0014] Preferably, in step S1, the cathode scrap steel undergoes crushing pretreatment, and the average length after crushing is 8-15 cm. The chromium, nickel, and ferrosilicon in the raw materials are in block form, while boron and lanthanide rare earth metals are added in powder or granular form.

[0015] Further, in step S1, the lanthanide rare earth metals include cerium, lanthanum, or a mixture of rare earth metals with cerium as the main component; the lanthanide rare earth metals are added in the form of rare earth silicon-iron alloys or rare earth nickel alloys.

[0016] Furthermore, in step S2, the shell-breaking hammer head is a solid structure made of Q235 steel, which includes a bottom frustum, a middle column, and a top small cylinder from bottom to top.

[0017] Further, in step S2, the number of rotations is 3-5, and the cumulative immersion time of the shell-piercing hammer in the alloy melt is 5-10 seconds. Specifically, the preheated shell-piercing hammer is vertically immersed in the alloy melt so that the working part to be coated (including the bottom frustum and the middle column) is immersed in the alloy melt. After rotating a specified number of times within the cumulative immersion time, it is removed to form a pre-coating layer.

[0018] Furthermore, in step S3, the preheating temperature of the extrusion molding die is 400-500℃.

[0019] Furthermore, in step S3, the extrusion molding die is composed of four modules, each of which is provided with a centering mechanism and a cavity for accommodating the bottom frustum and middle column of the shell-forming hammer; the contact surfaces of adjacent dies are provided with positioning pins.

[0020] Conventional forging and extrusion dies are typically in the form of a two-part die, but their compatibility with the hot extrusion process of this invention is poor. Specifically, they are not suitable for achieving uniform coverage of the protective layer, for setting up a centering mechanism, and require a large flash groove to accommodate more metal during two-part die extrusion. Furthermore, the loading direction at the edge of the two-part die is tangential to the cylindrical surface of the hammer, which, under the extrusion pressure of 200-300 MPa of this invention, causes significant tangential forces on the coating, potentially damaging the coating surface. In contrast, the four-part die structure design used in this invention is more rational, allowing for uniform hot extrusion of the coating from multiple directions, resulting in a more balanced pressure distribution and better performance in terms of coating forming effect, density, and reduced process costs.

[0021] Furthermore, in step S3, the cavity portion of the extrusion molding die is made of a high-hardness, high-temperature-resistant material to ensure the dimensional accuracy and durability of the cavity under high temperature and high pressure. Preferably, the extrusion molding die is made of tungsten steel.

[0022] Furthermore, in step S3, the shell-breaking hammerhead removed from the furnace opening is immediately placed into a preheated extrusion molding die, and pressure is applied to the outside of the extrusion molding die using a hydraulic press. This invention, by placing the shell-breaking hammerhead covered with molten alloy in a preheated extrusion molding die and applying high pressure, not only densifies and precisely shapes the coating, but more importantly, it promotes atomic interdiffusion between the coating alloy and the hammerhead substrate, forming a metallurgical bonding interface with a gradient transition in composition and microstructure. This significantly improves the coating's bonding strength and resistance to peeling.

[0023] Furthermore, in step S4, the post-processing includes welding and grinding the contact area between the shell-breaking hammer and the edge of the mold.

[0024] The second objective of this invention is to provide a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, which is prepared by the preparation method described in one of the objectives of this invention.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a method for preparing a low-adhesion, long-life shell-breaking hammer head based on cathode scrap steel reinforcement. The cathode scrap steel is used as the main raw material for coating. It is recycled and reused, which reduces material waste and carbon emissions. The alloy melt obtained by smelting is used as the coating material. Compared with other methods, it does not require a large amount of metal material to be crushed, which improves the preparation efficiency. The dip-plating-molding near-static forming technology can obtain a wear-resistant shell-breaking hammer head with coating in one go. The surface quality and metallurgical bonding strength of the coating are significantly better than other coating processes. This makes the protective layer on the surface of the shell-breaking hammer head less likely to fall off due to impact, thereby causing aluminum liquid pollution or excessive wear of the shell-breaking hammer head. Compared with the traditional casting hammer head-melting coating process, the process is simpler and more efficient, and the cost is greatly reduced.

[0026] (2) The low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement provided by this invention uses cathode scrap steel from the electrolytic aluminum industry as a high-carbon alloy resource to prepare a reinforced protective layer, achieving a synergistic breakthrough in performance and cost. In the coating system, the carbon in the cathode scrap steel and added elements such as chromium form a high-hardness, high-stability in-situ carbide reinforcing phase during smelting, constituting the wear-resistant skeleton of the coating; the unique composition and densification process endow the coating with extremely low electrolyte molten salt affinity, fundamentally inhibiting the "shelling and caking" phenomenon and significantly delaying corrosion and thermal shock failure caused by electrolyte adhesion; through the gradient metallurgical bonding interface formed by dip plating and hot extrusion, the coating and the substrate form an integrated structure, improving impact resistance and anti-stripping ability. These features together create the extraordinary durability of the shell-breaking hammerhead in the high-temperature, highly corrosive, and high-impact electrolytic aluminum environment. This product not only achieves a leapfrog improvement in the lifespan of key vulnerable components, but also provides the electrolytic aluminum industry with a component upgrade solution that combines excellent reliability, economy and environmental friendliness through the high-value utilization of cathode scrap steel, with broad application prospects. Attached Figure Description

[0027] Figure 1 A schematic flowchart of a method for preparing a low-adhesion, long-life shell-breaking hammer head based on cathode scrap steel reinforcement provided by the present invention. Figure 2 The present invention provides an uncoated Q235 alloy steel shell-breaking hammer head; Figure 3 This is a schematic diagram of the overall structure of a module in an extrusion molding die provided in an embodiment of the present invention; Figure 4 This is a side view of a module in an extrusion molding die provided in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the near-static forming operation using an extrusion molding die in an embodiment of the present invention. Figure 6This is a sample cross-section of the shell-breaking hammer head covered with a protective layer after molding, as shown in Embodiment 1 of the present invention. Figure 7 This is a SEM image of the junction between the protective layer and the shell-breaking hammer base in Embodiment 1 of the present invention; wherein, the upper part is the protective layer and the lower part is the shell-breaking hammer base; Figure 8 This is a sample cross-section of the shell-breaking hammer head covered with a protective layer after molding, as shown in Embodiment 2 of the present invention. Among them, 1-flash groove; 2-centering mechanism; 3-positioning pin. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a method for preparing a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, the process of which is shown in the schematic diagram below. Figure 1 As shown, it includes the following steps: Step 1: By weight, mix 75-85 parts of cathode scrap steel with a carbon content of 1 wt%-2 wt% with 6-10 parts of chromium, 6-10 parts of nickel, 1-1.5 parts of ferrosilicon, 0.8-1 parts of boron, and 0.7-1 parts of lanthanide rare earth metals, and smelt at 1400-1550℃. After the above raw materials are melted evenly, remove the slag from the surface to obtain an alloy melt. The cathode scrap steel is selected from cathode steel bars with a service life of 4-5 years that have been replaced during the regular overhaul of electrolytic cells in the electrolytic aluminum industry. The lanthanide rare earth metals include cerium, lanthanum, or a mixture of rare earth metals with cerium as the main component. The lanthanide rare earth metals are added in the form of rare earth ferrosilicon alloy or rare earth nickel alloy.

[0030] Step 2: Immerse the shell-piercing hammer head into the alloy melt, rotate it 3-5 times, and then remove it. The cumulative immersion time of the shell-piercing hammer head in the alloy melt is 5-10 seconds; Figure 2 As shown, the shell-breaking hammer head is a solid structure made of Q235 steel, comprising, from bottom to top, a bottom frustum, a middle column, and a top small cylinder. The bottom frustum has a height of 35-45mm and a top diameter of 75-85mm; the middle column has a height of 230-290mm and a diameter of 85-95mm; and the top small cylinder has a length of 35-45mm and a diameter of 75-95mm.

[0031] Step 3: Preheat the extrusion molding die to 400-500℃, and immediately put the removed shell-beating hammer into the preheated extrusion molding die, and extrude for 10-20 seconds under a pressure of 200-300MPa; Step 4: Cool the extruded hammer head to room temperature, and then weld and grind the contact area between the hammer head and the mold edge to obtain a hammer head covered with a reinforced coating.

[0032] The structure of the extrusion molding die used in step 3 is as follows: Figure 3-5 As shown, the extrusion molding die is composed of four modules made of tungsten steel. Each module has a centering mechanism 2 and a cavity to accommodate the bottom frustum and middle column of the extrusion hammer. The centering mechanism 2 ensures uniform coating thickness around the perimeter. The contact surfaces of adjacent dies are equipped with positioning pins 3 and flash grooves 1. The flash grooves 1 accommodate excess molten metal, and the positioning pins 3 ensure the position and connection between the modules. In use, the inner cavities of the four modules enclose the bottom frustum and middle column of the extrusion hammer through the centering mechanism 2 and positioning pins 3. The distance between the inner wall of the extrusion molding die and the extrusion hammer is 1.5-2mm to ensure a protective layer thickness of approximately 1.5-2mm. The flash groove 1 is 8-10mm long and 1-1.6mm high. Hydraulic presses are used simultaneously on the outside of the four modules in the direction of the extrusion hammer axis.

[0033] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0034] The main parameters and variables of the various embodiments and comparative examples of the present invention are shown in Table 1 below.

[0035] Table 1

[0036] In the various embodiments of this invention, the cathode scrap steel used specifically comes from cathode steel bars that have been replaced during major overhauls of 200-350kA electrolytic cells, have served for 4-5 years, and are now scrapped. During long-term high-temperature electrolysis, the surface of these cathode steel bars undergoes significant carburization, forming a high-carbon layer with a carbon content of 1.0wt%-2.0wt%. The surface is covered with a small amount of oxide scale, electrolyte, and carbon residues. Before use, most of the surface deposits are removed through mechanical cleaning.

[0037] Example 1 This embodiment provides a method for preparing a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, including the following steps: Step 1: Weigh 8.48 kg of cathode scrap steel (cathode scrap steel replaced during the overhaul of a 200KA electrolytic cell, which has been in service for 4 years and has a carbon content of 1.3 wt%), 0.6 kg of nickel, 0.6 kg of chromium, 100 g of boron, 0.15 kg of ferrosilicon, and 70 g of lanthanide rare earth metals. Put the above raw materials into a smelting furnace and melt them at a temperature of 1450 degrees Celsius until they reach a molten state. Remove the slag from the surface to obtain an alloy melt. Step 2: Immerse the shell-piercing hammer head vertically into the plating solution, rotate it 3 times, and remove it after a total time of 10 seconds; Step 3: Preheat the extrusion molding die to 400℃, and immediately put the removed shell-beating hammer into the preheated extrusion molding die and extrude for 10 seconds under a pressure of 200MPa. Step 4: Cool the extruded hammer head to room temperature, then weld and grind the contact area between the hammer head and the mold edge to obtain a hammer head covered with a reinforcing coating. A cross-sectional view of this hammer head is shown below. Figure 6 As shown, the SEM image of the junction between the protective layer and the shell-breaking hammerhead substrate is as follows. Figure 7 As shown, the thickness of the protective layer is 1.65 mm.

[0038] Example 2 This embodiment provides a method for preparing a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, including the following steps: Step 1: Weigh 7.72 kg of cathode scrap steel (cathode scrap steel replaced during the overhaul of a 350kA electrolytic cell, which has been in service for 5 years and has a carbon content of 1.8wt%), 1.0 kg of nickel, 1.0 kg of chromium, 80 g of boron, 0.1 kg of ferrosilicon, and 100 g of lanthanide rare earth metals. Put the above raw materials into a smelting furnace and melt them at a temperature of 1500 degrees Celsius until they reach a molten state. Remove the slag from the surface to obtain an alloy melt. Step 2: Immerse the shell-breaking hammer head vertically into the plating solution, rotate it 4 times, and remove it after a total time of 8 seconds; Step 3: Preheat the extrusion molding die to 500℃, and immediately put the removed shell-breaking hammer into the preheated extrusion molding die and extrude it for 15 seconds under a pressure of 300MPa. Step 4: Cool the extruded hammer head to room temperature, then weld and grind the contact area between the hammer head and the mold edge to obtain a hammer head covered with a reinforcing coating. A cross-sectional view of this hammer head is shown below. Figure 8 As shown, the thickness of the protective layer is 1.87 mm.

[0039] Example 3 This embodiment provides a method for preparing a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, including the following steps: Step 1: Weigh 8.1 kg of cathode scrap steel (cathode scrap steel replaced during the overhaul of a 200KA electrolytic cell, which has been in service for 5 years and has a carbon content of 1.7 wt%), 0.8 kg of nickel, 0.8 kg of chromium, 100 g of boron, 120 g of ferrosilicon, and 80 g of lanthanide rare earth metals. Put the above raw materials into a smelting furnace and melt them at a temperature of 1550 degrees Celsius until they reach a molten state. Remove the slag from the surface to obtain an alloy melt. Step 2: Immerse the shell-breaking hammer head vertically into the plating solution, rotate it 4 times, and remove it after a total time of 9 seconds; Step 3: Preheat the extrusion molding die to 450℃, and immediately put the removed shell-beating hammer into the preheated extrusion molding die and extrude for 15 seconds under a pressure of 250MPa. Step 4: Cool the extruded hammer head to room temperature, and then weld and grind the contact area between the hammer head and the mold edge to obtain a hammer head covered with a reinforced coating. The thickness of the protective layer is 1.76mm.

[0040] Comparative Example 1 This comparative example provides a method for preparing a reinforcing coating on the surface of a shell-beating hammer head using cast steel as the main raw material and employing an electric arc cladding method, including the following steps: Step 1: Weigh 8.5kg of cast steel, 1kg of nickel, 1kg of chromium, 100g of boron, 0.15kg of ferrosilicon, and 70g of lanthanide rare earth metals. After crushing the above raw materials into powder, attach them to the surface of the shell-breaking hammer head by electric arc cladding with a power of 7kW and a protective layer thickness of 7mm.

[0041] Step 2: After the cladding is completed, inspect the aforementioned protective layer, weld any missing parts of the protective layer, and grind the entire protective layer evenly until the surface is smooth to obtain the cladding-strengthened shell-breaking hammerhead.

[0042] Comparative Example 2 No strengthening treatment is applied to the shell-breaking hammer head of the Q235 matrix; that is, an unstrengthened shell-breaking hammer head is used.

[0043] Application performance testing In a 350kA electrolytic cell at an aluminum and electricity company in Ningxia, the shell-breaking hammerhead prepared according to the embodiments of the present invention was subjected to application performance tests, and the application effects were compared with those of Comparative Examples 1 and 2. The tests showed that the shell-breaking hammerhead prepared using the method provided by the present invention not only has high production efficiency and low cost, but also exhibits improved overall hardness, less electrolyte adhesion, and a significantly extended service life. Table 2 shows the specific test data.

[0044] Table 2

[0045] Note: In the table above, the preparation time refers to the time required from the start of processing to the cooling and solidification of the protective layer. Since Comparative Example 2 has no processing flow, it is not compared.

[0046] In summary, the method for preparing the reinforced shell-breaking hammerhead provided by this invention uses cathode scrap steel as the main raw material and employs a short-process technology of smelting-immersion coating-hot extrusion to successfully prepare a reinforced protective layer with both high hardness and low electrolyte adhesion. As shown in Table 2, compared with the conventional strengthening process (Comparative Example 1), the preparation method provided by this invention maintains essentially the same hardness (HRC 55-58) while reducing the electrolyte adhesion rate to below 5%, thereby achieving a significant increase in service life (over 800 days). This fully demonstrates that this invention, targeting the shell-breaking process of electrolytic aluminum, achieves positive results in extending the service life of the shell-breaking hammerhead by reducing electrolyte adhesion through a special formula and process. Furthermore, by directly utilizing cathode scrap steel as the main raw material for the coating, it achieves a significant reduction in raw material costs and high-value utilization of solid waste.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, characterized in that, Includes the following steps: S1. By weight, 75-85 parts of cathode scrap steel with a carbon content of 1 wt%-2 wt% are mixed with 6-10 parts of chromium, 6-10 parts of nickel, 1-1.5 parts of ferrosilicon, 0.8-1 parts of boron and 0.7-1 parts of lanthanide rare earth metals, and smelted at 1400-1550℃. After the above raw materials are melted evenly, the surface slag is removed to obtain the alloy melt. S2. Immerse the shell-breaking hammer head into the alloy melt, rotate it several times, and then remove it. S3. Immediately place the removed shell-breaking hammer into the preheated extrusion molding die and extrude it for 10-20 seconds under a pressure of 200-300MPa. S4. Cool the extruded shell-beating hammer head to room temperature and then perform post-processing to obtain a shell-beating hammer head covered with a reinforced coating.

2. The preparation method according to claim 1, characterized in that, In step S1, the cathode scrap steel is selected from cathode steel bars with a service life of 4-5 years that are replaced during the regular overhaul of electrolytic cells in the aluminum electrolytic industry.

3. The preparation method according to claim 1, characterized in that, In step S1, the lanthanide rare earth metals include cerium, lanthanum, or a mixture of rare earth metals with cerium as the main component; the lanthanide rare earth metals are added in the form of rare earth silicon-iron alloys or rare earth nickel alloys.

4. The preparation method according to claim 1, characterized in that, In step S2, the shell-breaking hammer head is a solid structure made of Q235 steel, which includes a bottom frustum, a middle column and a top small cylinder from bottom to top.

5. The preparation method according to claim 1, characterized in that, In step S2, the number of rotations is 3-5, and the cumulative immersion time of the shell-piercing hammer in the alloy melt is 5-10 seconds.

6. The preparation method according to claim 1, characterized in that, In step S3, the preheating temperature of the extrusion molding die is 400-500℃.

7. The preparation method according to claim 1, characterized in that, In step S3, the extrusion molding die is composed of four modules; each module is provided with a centering mechanism and a cavity to accommodate the bottom frustum and middle column of the shell-forming hammer; the contact surface of adjacent dies is provided with positioning pins.

8. The preparation method according to claim 1, characterized in that, In step S3, the extrusion molding die is made of tungsten steel.

9. The preparation method according to claim 1, characterized in that, In step S4, the post-processing includes welding and grinding the contact area between the shell-breaking hammer and the edge of the mold.

10. A low-adhesion, long-life shell-breaking hammerhead based on cathode scrap steel reinforcement, characterized in that, It is prepared by the method according to any one of claims 1-9.

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