Method for preparing an erosion-resistant coating material and application of the same to a shell-breaking hammer head of a reinforced electrolytic cell

Abstract

The application provides a preparation method of an anti-abrasion coating material, which comprises the following steps: configuration of raw material powder, cleaning of a substrate surface, pre-alloy paste coating, plasma cladding for preparing a coating, and cleaning of a cladding coating surface. The raw material powder comprises the following components in percentage by mass: Ni: 15-19%, Cr: 23-27%, Al: 3-6%, Si: 1-2%, Si3N4: 2-4%, and the balance of Fe. The prepared coating material is well combined with the substrate, has no composition segregation and non-wetting phenomenon, the coating structure is mainly austenite, contains skeleton ferrite structure, and has in-situ generated aluminum nitride particle precipitation phase, the existence of the dual-phase and aluminum nitride particles enhances the wear resistance and aluminum liquid corrosion resistance of the coating. The preparation method of the anti-abrasion coating material is used for strengthening the crust breaking hammer head of an electrolytic cell, which can significantly improve the service life of the crust breaking hammer head of the electrolytic cell, reduces the production cost and labor intensity of the enterprise, and has a wide popularization and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of aluminum smelting technology, specifically relating to a method for preparing a wear-resistant coating material, and also relating to the application of the above-mentioned method for preparing a wear-resistant coating material in a shell-breaking hammerhead for an enhanced electrolytic cell. Background Technology

[0002] The prebaked anode aluminum electrolytic cell with central feeding is a major piece of equipment in the production of domestic electrolytic aluminum enterprises. The shell-breaking and feeding system is responsible for opening the feed port of the prebaked anode aluminum electrolytic cell so that the alumina raw material can smoothly enter the electrolyte and maintain the continuous and normal operation of the aluminum electrolysis production process. Therefore, it is one of the important structures in the electrolytic cell.

[0003] The shell-breaking hammer, a key component of the shell-breaking and blanking system, operates for extended periods in environments characterized by strong magnetic fields, high temperatures, high currents, and highly corrosive media. On average, it impacts and rubs against the high-hardness alumina shell every 68 seconds, and is frequently corroded by high-temperature cryolite, molten alumina electrolyte salts, and molten aluminum, resulting in rapid wear and tear. In my country, shell-breaking hammers are generally made of ordinary Q235 cast steel, which has poor wear and corrosion resistance and a short service life. The rapid consumption and frequent replacement of shell-breaking hammers not only increase the production cost of electrolytic aluminum but also increase the workload of workers and pose safety hazards. Furthermore, the wear and corrosion of the hammer material introduces impurities into the molten aluminum, reducing the purity and quality of the aluminum ingots. Therefore, developing wear-resistant materials and applying them to strengthen shell-breaking hammers is crucial for electrolytic aluminum production.

[0004] Many researchers have explored ways to improve the lifespan of the shell-breaking hammer. Currently, research on improving the lifespan of the shell-breaking hammer mainly focuses on the following three directions: (1) Optimization of application process: Optimize the process of using the component and reduce the contact time of the component with the molten aluminum, such as increasing the back pressure in the exhaust pipe and reducing the immersion time of the shell-breaking hammer in the molten aluminum and electrolyte. Increase the number of work shifts and rotate the work to reduce the service time of the component. However, as a mature industry, the daily process of electrolytic aluminum has been optimized and coordinated over a long period of time. Protecting the component through process control methods usually causes a chain of problems. (2) Changes in structure: Change the structure of the component or combine different metals or metal-non-metals using mechanical structure to increase the component's resistance to aluminum corrosion and electrolyte crusting wear. For example, increase the weight of the shell-breaking hammer, increase the impulse and momentum, and change the hammer head to a spherical shape to reduce electrolyte adhesion or use a bimetallic shell-breaking hammer with ordinary carbon steel on the upper part and heat-resistant steel or ceramic mechanically bonded to the lower part. Although structural changes can usually improve the service life of the component, the mechanical combination of bimetals or different materials affects the bonding strength and has a high cost, making it unsuitable for large-scale application. (3) Surface modification: Using materials more resistant to aluminum molten corrosion to replace the original materials in contact with the aluminum molten material reduces the corrosion rate of the components. Commonly used surface modification methods include carburizing, nitriding, and boronizing. However, because the carburized layer is relatively thin, generally only a few tens to hundreds of micrometers, the surface modification method of carburizing has very limited effect on improving the service life of the hammerhead. Thermal spraying is another commonly used surface modification method. However, the coating and the substrate are mechanically bonded. During the use of the hammerhead, under the frequent thermal stress and impact, the coating will peel off from the surface in pieces and fail. Although sandblasting can enhance the bonding strength, sandblasting often leaves sand particles on the workpiece surface. Therefore, thermal spraying technology also has limited effect on improving the service life of the hammerhead.

[0005] Based on this, a more effective surface treatment method is provided compared with carburizing, nitriding, boronizing and thermal spraying, so as to prepare a high alloy composite layer with a larger thickness and higher metal element content on the surface of the hammerhead, thereby effectively improving the wear resistance, high temperature resistance and corrosion resistance of the shell-breaking hammerhead and extending its service life. This is of great significance for ensuring the continuous and stable production of electrolytic aluminum and is also a technical problem that researchers urgently need to solve. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing a coating material with excellent wear resistance, high temperature resistance, and corrosion resistance.

[0007] The second objective of this invention is to provide a method for strengthening the shell-forming hammerhead of an electrolytic cell using a wear-resistant coating material.

[0008] The third objective of this invention is to provide an electrolytic cell shell-breaking hammer head with excellent wear resistance, high temperature resistance, and corrosion resistance, and a long service life.

[0009] One of the technical solutions adopted to achieve the objective of this invention is: to provide a method for preparing a wear-resistant coating material, comprising the following steps:

[0010] S1. Prepare raw material powder according to the following mass percentages: Ni: 15%~19%, Cr: 23%~27%, Al: 3%~6%, Si: 1%~2%, Si3N4: 2%~4%, with the balance being Fe, and the total amount of each raw material is 100%.

[0011] S2. Fe, Cr, Ni, Al and Si in the raw material powder are mixed and ball-milled to obtain alloyed powder; the alloyed powder is mixed with Si3N4 powder, a process control agent is added and wet milling is performed, the product is dried and sieved to obtain mixed powder;

[0012] S3. Ethyl cellulose and turpentine percolate are mixed in a certain proportion to obtain an adhesive. The mixed powder and the adhesive are mixed in a certain proportion to obtain an alloy paste.

[0013] S4. The alloy paste is melted onto the surface of the substrate to form a wear-resistant coating material.

[0014] The general idea of ​​the preparation method of the wear-resistant coating material provided by the present invention is as follows:

[0015] First, in order to meet the requirements of providing the substrate with resistance to aluminum liquid corrosion and high wear resistance, the present invention uses the following raw materials as coating materials, which contain 23% to 27% chromium, 15% to 19% nickel, 3% to 6% aluminum, 1% to 2% silicon, 2% to 4% silicon nitride, and the balance iron by mass fraction.

[0016] Secondly, by ball milling the Fe, Cr, Ni, Al, and Si in the raw material powder, alloyed powder is obtained. This step yields a coating raw material with dissolved alloying element powder, reducing non-wetting and component segregation during the cladding process. Simultaneously, the pre-coated powder avoids the stratification problem caused by the powder feed gas during conventional powder spraying processes, reducing macroscopic component segregation. Then, the alloyed powder is further mixed with Si3N4 powder and wet-milled under the action of a process control agent to obtain a mixed powder. The aforementioned ball milling process without process control agent is to mechanically alloy the alloy powder, producing a powder in a solid solution state. The subsequent wet milling process with process control agent is only to refine the powder and improve its morphology, preventing Si3N4 from decomposing during ball milling. It aims to preserve Si and N released during the thermal decomposition of Si and N in the cladding process, and utilize the in-situ reaction between N and Al in the coating to produce granular AlN, strengthening the cladding coating. Next, an adhesive is obtained by mixing ethyl cellulose and turpentine with alcohol, and the mixed powder and adhesive are mixed in a certain proportion to form an alloy paste for use in subsequent processes.

[0017] Finally, the alloy paste is applied to the pretreated substrate surface to form an alloy paste surface layer. Plasma cladding is then used to clad the substrate with the alloy paste surface layer. The nitrogen released from the decomposition of silicon nitride in the alloy paste, combined with the large heat input during plasma cladding and the dilution effect of the base material on the coating, forms a dual-phase cladding coating matrix dominated by austenite and containing a skeletal ferrite structure. The presence of the dual phases not only enhances the wear resistance of the coating but also, with the large-scale austenite-ferrite grain boundaries hindering Fe-Al atom diffusion, further improves the material's resistance to aluminum melt corrosion. Furthermore, the nitrogen released after the decomposition of silicon nitride combines with aluminum to generate a large number of aluminum nitride precipitates in situ. These aluminum nitride precipitates act as heterogeneous nucleation sites, refining the coating microstructure. Under the combined effect of grain refinement and second-phase strengthening, the coating strength and wear resistance are further enhanced. Simultaneously, the in-situ generation of aluminum nitride particles avoids the problems of non-wetting between the coating and particles and thermal deformation cracks that may occur with the direct addition of the hard aluminum nitride phase.

[0018] Furthermore, the substrates applicable to the preparation method provided by this invention include low-alloy steels such as Q235, Q245, and H13. In addition, since the wear-resistant coating material obtained by this invention is mainly composed of iron and contains nickel and chromium, it bonds well with the substrate prepared from Q235 material and is easy to clad, making it particularly suitable for surface strengthening of Q235 material.

[0019] Preferably, in step S1, the raw material powder has a mesh size of 100 to 300 mesh.

[0020] Preferably, in step S2, the mass ratio of raw material powder to grinding balls in the ball milling process is 1:10; the ball milling process is carried out under a protective atmosphere, and the rotation speed of the ball milling process is 280-300 rpm. More preferably, after every 60 minutes of ball milling, the ball milling is stopped for 8-10 minutes, and then the ball milling continues, with a total ball milling time of 20-48 hours. More preferably, samples are taken and analyzed at 3, 8, 13, and 20 hours of ball milling to determine the mechanical alloying effect of the powder.

[0021] Furthermore, in step S2, the process control agent for wet milling is selected from one or more combinations of anhydrous ethanol, deionized water, and n-hexane; preferably, the volume ratio of wet milling raw material to process control agent is 1:1.

[0022] Preferably, in step S2, the rotation speed of the wet grinding process is 280-300 rpm, and the wet grinding time is 2-4 hours.

[0023] Furthermore, in step S2, the product is dried at a temperature of 50–60°C for 24 hours; and the sieve mesh size is 100–300 mesh.

[0024] Preferably, in step S3, the mass ratio of ethyl cellulose to turpentine percolate in the adhesive is (6-8):(92-94), and the mixed powder is mixed with the adhesive at a mass ratio of (8-12):1 to obtain the alloy paste. In this invention, by controlling the ratio of ethyl cellulose to turpentine percolate in the adhesive, the viscosity and adhesive strength of the adhesive can be controlled. Under the above conditions, the resulting alloy paste has the best overall performance and is more conducive to subsequent plasma cladding operations.

[0025] Further, step S4 includes: applying the alloy paste with a thickness of 6-8 mm to the pretreated substrate surface to form an alloy paste surface layer, and drying it at 50-70°C; and using plasma cladding to clad the substrate with the alloy paste surface layer to form a wear-resistant coating material on the substrate surface. Preferably, the thickness of the alloy paste surface layer is 7 mm; the drying temperature is 55-65°C, and the drying time is 20-28 hours; the parameters of plasma cladding include: a distance of 6-10 mm between the cladding gun tip and the alloy paste surface layer, a cladding speed of 6-10 mm / s, and a cladding current of 180-220 A.

[0026] The second objective of this invention is achieved by providing a method for strengthening the shell-breaking hammerhead of an electrolytic cell, comprising: preparing the wear-resistant coating material on the surface of the shell-breaking hammerhead using the preparation method described in one objective of this invention, wherein the specific preparation method is as follows:

[0027] S1. Prepare raw material powder according to the following mass percentages: Ni: 15%~19%, Cr: 23%~27%, Al: 3%~6%, Si: 1%~2%, Si3N4: 2%~4%, with the balance being Fe, and the total amount of each raw material is 100%.

[0028] S2. Fe, Cr, Ni, Al and Si in the raw material powder are mixed and ball-milled to obtain alloyed powder; the alloyed powder is mixed with Si3N4 powder, a process control agent is added and wet milling is performed, the product is dried and sieved to obtain mixed powder;

[0029] S3. Ethyl cellulose and turpentine percolate are mixed at a mass ratio of (6-8):(92-94) to obtain an adhesive. The mixed powder and the adhesive are mixed at a mass ratio of (8-12):1 to obtain an alloy paste.

[0030] S4. Apply a certain thickness of the alloy paste to the surface of the pretreated shell-breaking hammer head to form an alloy paste surface layer, and dry it. Use plasma cladding to control the distance between the cladding gun head and the alloy paste surface layer to be 6-10 mm, the cladding speed to be 6-10 mm / s, and the cladding current to be 180-220 A. Clamping is performed on the shell-breaking hammer head with the alloy paste surface layer to form a wear-resistant coating material on the surface of the shell-breaking hammer head.

[0031] In the above method, the shell-forming hammerhead is strengthened through a series of steps including powder composition preparation, mechanical alloying, alloy paste preparation, and plasma cladding. This invention controls the content of each component (Cr, Ni, Al, and Si3N4) in the alloy powder to form an austenitic structure in the cladding coating, thereby increasing its high-temperature performance. Furthermore, this invention employs a mechanical alloying method to form a solid solution, solving problems such as insufficient resistance to aluminum melt corrosion in coatings formed by conventional alloy powders, the formation of hard nitride phases during surface treatment, and the inability of molten metal droplets to wet the base material during the cladding process, thus failing to form an effective cladding layer.

[0032] Furthermore, considering that the microstructure of Si3N4 powder is elongated and rod-shaped, while other alloy powders are spherical, traditional powder spraying methods for cladding can cause powder to stratify in the air, resulting in an uneven composition of the cladding coating. Therefore, this invention uses a method of applying a pre-made alloy paste to the base material before welding, effectively reducing powder stratification in the air and ensuring the uniformity of the alloy composition. In addition, this invention optimizes the plasma cladding parameters to generate a suitable cladding current, ensuring sufficient heat in the molten pool to achieve rapid and complete decomposition of Si3N4, producing sufficient AlN. On the one hand, this avoids the adverse effects of residual Si3N4 on wettability and prevents cracks from forming in the coating; on the other hand, it ensures sufficient consumption of Al elements, preventing residual Al elements from transforming the cladding coating structure into ferrite and reducing its high-temperature resistance, thus ensuring the overall performance of the final coating.

[0033] Furthermore, during the plasma cladding process in step S4, the cladding path is routed around the large cylindrical section of the hammerhead, starting from the direction of the small cylindrical section. After completing one full circle, it moves towards the distal end with a 50% overlap rate to complete the preparation of the wear-resistant coating material on the surface of the hammerhead. Specifically, for a cylindrical hammerhead, one end face has a section of cylinder with a smaller diameter. The cladding path starts from the end face of the hammerhead near the small-diameter cylinder and moves around the hammerhead, gradually towards the other end face. During the cladding process, the hammerhead rotates while the cladding gun remains stationary. The cladding path proceeds in circles around the hammerhead, with each circle covering 40% to 60% of the previously clad path (i.e., an overlap rate of 40% to 60%), until the cladding layer completely covers the entire hammerhead, at which point the cladding process is complete.

[0034] In this invention, a special cladding path is used to prepare a wear-resistant coating material on the surface of the hammer head. This ensures that the cladding start and arc initiation stages are in the non-primary working area of ​​the hammer head, thus avoiding insufficient welding quality caused by arc initiation that could affect the service life of the hammer head.

[0035] Furthermore, since the penetration depth generated by plasma cladding includes the molten base material and the reinforcing material produced by the fusion of welding materials, the final thickness of the wear-resistant coating material will be slightly higher than the thickness of the alloy paste surface layer. Preferably, the thickness of the wear-resistant coating material formed on the surface of the shell-breaking hammer head is 7-9 mm.

[0036] Preferably, during mass production, a small number of reinforced electrolytic cell shell-forming hammerhead samples can be prepared first, and the coating of the samples can be sampled and analyzed. Specifically, the coating of the shell-forming hammerhead samples prepared by the first cladding is cut and sampled using a wire cutting device to characterize the microstructure, grain morphology, phase composition, and elemental distribution, and then the hardness, tribological wear properties, and resistance to aluminum melt corrosion are tested. Based on this, the preparation process parameters are fine-tuned, and the performance of the sample coating test and the coating microstructure characterization results, as well as the performance requirements and cost control in actual use, are comprehensively considered to fine-tune the process parameters such as the component ratio, cladding current, and cladding rate during coating material preparation.

[0037] The technical solution adopted to achieve the third objective of this invention is to provide an electrolytic cell shell-breaking hammer head, which is made by the method described in the second objective of this invention.

[0038] In this invention, the surface of the electrolytic cell's shell-breaking hammerhead is coated with a wear-resistant coating material of a certain thickness and a higher metal element content. This coating material improves the wear resistance, high temperature resistance, and corrosion resistance of the shell-breaking hammerhead, effectively extending its service life and reducing the production cost of electrolytic aluminum.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) The method for preparing the wear-resistant coating material provided by this invention uses a self-made mixed powder and further prepares an alloy paste. The nitrogen element released by the decomposition of silicon nitride (2wt.% to 4wt.% of the powder), combined with the large heat input of the plasma cladding process and the dilution effect of the base material on the coating, forms a dual-phase cladding coating matrix with austenite as the main component and a skeleton-like ferrite structure. The presence of the dual phase enhances the wear resistance of the coating. The large-scale austenite-ferrite grain boundaries hinder the diffusion of Fe-Al atoms and improve the material's resistance to aluminum liquid corrosion. At the same time, the nitrogen element released after the silicon nitride decomposes combines with aluminum element to generate a large number of aluminum nitride precipitates in situ. The aluminum nitride precipitates act as heterogeneous nucleation cores, refining the coating structure. Under the combined effect of fine grain strengthening and second phase strengthening, the coating strength is improved, the wear resistance is enhanced, and the in-situ generation of aluminum nitride particles avoids the problems of non-wetting of coating and particles and thermal deformation cracks that may occur when directly adding aluminum nitride hard phase.

[0041] (2) This invention provides a method for strengthening the shell-forming hammerhead of an electrolytic cell using a wear-resistant coating material. A wear-resistant coating material is formed on the surface of the shell-forming hammerhead. This coating material is mainly composed of iron and includes nickel and chromium elements. It bonds well with the Q235 material substrate of the shell-forming hammerhead and is easy to clad. Furthermore, the raw material powder is ball-milled and mechanically alloyed to obtain a coating raw material with dissolved alloy element powder, reducing non-wetting and component segregation during the cladding process. The pre-coated powder avoids the problem of powder stratification under the influence of the powder feeding gas during the conventional powder spraying process for preparing the cladding coating, thus reducing macroscopic component segregation.

[0042] (3) The electrolytic cell shell-breaking hammer head prepared by the present invention has excellent wear resistance, high temperature resistance and corrosion resistance. Its service life reaches more than 12 months. Compared with similar hammer heads, the service life is increased by at least 4 times. It can significantly reduce the production cost of enterprises and the labor intensity of employees, and has broad prospects for promotion and application. Attached Figure Description

[0043] Figure 1 A schematic flowchart illustrating a method for strengthening an electrolytic cell shell-forming hammerhead using a wear-resistant coating material, provided in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of plasma cladding on the surface of a shell-breaking hammer head, provided in an embodiment of the present invention.

[0045] Figure 3 The XRD patterns of the wear-resistant coating materials obtained in Examples 1-3 of this invention are shown below.

[0046] Figure 4 This is a metallographic image of the microstructure of the wear-resistant coating material obtained in Example 1 of the present invention. Detailed Implementation

[0047] 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.

[0048] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0049] 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.

[0050] The composition (wt.%) of the raw material powder in step 1 of Examples 1-3 of the present invention is shown in Table 1 below.

[0051] Table 1

[0052] Ni Cr Al Si <![CDATA[Si3N4]]> Fe Example 1 17 25 3 1 2 52 Example 2 15 23 4 1 3 54 Example 3 19 27 6 1 4 43

[0053] Example 1

[0054] This embodiment provides a method for strengthening the shell-breaking hammer head of an electrolytic cell using a wear-resistant coating material. The process flow is as follows: Figure 1 As shown, it includes the following steps:

[0055] Step 1: Prepare raw material powder. Take 200-mesh pure powder raw materials according to the proportions shown in Table 1. Mix Fe, Cr, Ni, Al, and Si and put them into a planetary ball mill. Prepare grinding balls at a powder-to-ball mass ratio of 1:10. Use Ar gas as the protective gas and the ball milling speed is 280 rpm. Rest for at least 10 minutes after every 60 minutes of ball milling. The total dry ball milling time is 24 hours. Take samples at 3, 8, 13, and 20 hours after ball milling to analyze the mechanical alloying effect of the powder. Mix the alloyed powder with Si3N4 powder and wet mill for 3 hours with ethanol as the process control agent. Dry the mixed powder after ball milling at 50°C for 24 hours, and then sieve the powder through 100-300 mesh sieves.

[0056] Step 2: Clean the surface of the shell-breaking hammer head. Use an angle grinder to grind the surface of the newly made shell-breaking hammer head of Q235 material until the new metal surface is exposed, and then use coarse sandpaper to polish it.

[0057] Step 3: Pre-coat alloy paste. Mix ethyl cellulose and turpentine alcohol in a mass ratio of 7:93 to prepare a paste adhesive. Mix the ball-milled powder with the adhesive in a mass ratio of 10:1 to prepare a pre-coat alloy paste. Apply a 6 mm thick layer of alloy paste to the surface of the shell-beating hammer after grinding. Dry the shell-beating hammer coated with alloy paste at 50°C for 36 hours.

[0058] Step 4: Plasma cladding to prepare the coating. The plasma cladding gun tip is 6 mm away from the alloy paste. The cleaned shell-breaking hammer head is clad at a cladding speed of 6 mm / s and a cladding current of 200A. The overlap rate is 40%. The cladding path circles the large cylindrical section of the hammer head, starting from the direction of the small cylindrical section of the hammer head. After completing one full circle, it continues to move.

[0059] (like Figure 2 (As shown)

[0060] Step 5: Clean the cladding coating surface. Tap the cladding coating to remove surface slag; use grinding equipment to grind and clean the cladding coating surface until the surface is smooth.

[0061] Example 2

[0062] This embodiment provides a method for strengthening the shell-breaking hammer head of an electrolytic cell using a wear-resistant coating material. The process flow is as follows: Figure 1 As shown, it includes the following steps:

[0063] Step 1: Prepare raw material powder. Take 250-mesh pure powder raw materials: Fe, Cr, Ni, Al, and Si according to the proportions shown in Table 1. Mix them and put them into a planetary ball mill. Prepare grinding balls at a powder-to-ball mass ratio of 1:10. Use Ar gas as the protective gas and the ball milling speed is 300 rpm. Rest for at least 10 minutes after every 60 minutes of ball milling. The total dry ball milling time is 20 hours. Take samples at 3, 8, 13, and 20 hours after ball milling to analyze the mechanical alloying effect of the powder. Mix the alloyed powder with Si3N4 powder and wet mill for 3 hours with ethanol as the process control agent. Dry the mixed powder after ball milling at 50°C for 24 hours, and then sieve the powder through 100-300 mesh sieves.

[0064] Step 2: Clean the surface of the shell-breaking hammerheads. Use an angle grinder to grind the surface of the six shell-breaking hammerheads made of Q235 material with minor corrosion and wear until a brand new metal surface is exposed, and then use coarse sandpaper to polish them.

[0065] Step 3: Pre-coat alloy paste. Mix ethyl cellulose and turpentine alcohol in a mass ratio of 7:93 to prepare a paste adhesive. Mix the ball-milled powder with the adhesive in a mass ratio of 10:1 to prepare a pre-coat alloy paste. Apply a 7 mm thick layer of alloy paste to the surface of the shell-beating hammer after grinding. Dry the shell-beating hammer coated with alloy paste at 60°C for 24 hours.

[0066] Step 4: Plasma cladding to prepare the coating. The plasma cladding gun tip is 8 mm away from the alloy paste. The cleaned shell-breaking hammerhead is clad at a cladding speed of 10 mm / s and a cladding current of 220 A, with an overlap rate of 50%. The cladding path circles the large cylindrical section of the hammerhead, starting from the direction of the small cylindrical section, and continues moving after completing one full circle. (e.g.) Figure 2 (As shown)

[0067] Step 5: Clean the cladding coating surface. Tap the cladding coating to remove surface slag; use grinding equipment to grind and clean the cladding coating surface until the surface is smooth.

[0068] Example 3

[0069] This embodiment provides a method for strengthening the shell-breaking hammer head of an electrolytic cell using a wear-resistant coating material. The process flow is as follows: Figure 1 As shown, it includes the following steps:

[0070] Step 1: Prepare raw material powder. Take 250-mesh pure powder raw materials: Fe, Cr, Ni, Al, and Si according to the proportions shown in Table 1. Mix them and put them into a planetary ball mill. Prepare grinding balls at a powder-to-ball mass ratio of 1:10. Use Ar gas as the protective gas and the ball milling speed is 290 rpm. Rest for at least 10 minutes after every 60 minutes of ball milling. The total dry ball milling time is 20 hours. Take samples at 3, 8, 13, and 20 hours after ball milling to analyze the mechanical alloying effect of the powder. Mix the alloyed powder with Si3N4 powder and wet mill for 3 hours with ethanol as the process control agent. Dry the ball-milled mixed powder at 50°C for 24 hours, and then sieve the powder through 100-300 mesh sieves.

[0071] Step 2: Clean the surface of the shell-breaking hammer. Use an angle grinder to grind the surface of the 12 shell-breaking hammers made of Q235 material until the new metal surface is exposed, and then use coarse sandpaper to polish them.

[0072] Step 3: Pre-coat alloy paste. Mix ethyl cellulose and turpentine alcohol in a mass ratio of 7:93 to prepare a paste adhesive. Mix the ball-milled powder with the adhesive in a mass ratio of 10:1 to prepare a pre-coat alloy paste. Apply an 8 mm thick layer of alloy paste to the surface of the shell-beating hammer after grinding. Dry the shell-beating hammer coated with alloy paste at 70°C for 24 hours.

[0073] Step 4: Plasma cladding to prepare the coating. The plasma cladding gun tip is 10 mm away from the alloy paste. The cleaned shell-breaking hammerhead is clad at a cladding speed of 10 mm / s and a cladding current of 220 A, with an overlap rate of 60%. The cladding path circles the large cylindrical section of the hammerhead, starting from the direction of the small cylindrical section, and continues moving after completing one full circle. (e.g.) Figure 2 (As shown)

[0074] Step 5: Clean the cladding coating surface. Tap the cladding coating to remove surface slag; use grinding equipment to grind and clean the cladding coating surface until the surface is smooth.

[0075] Performance and Characterization

[0076] The wear-resistant coating materials obtained in Examples 1-3 were sampled and analyzed (samples of the initial cladding hammerhead coating were cut and taken using a wire cutting device), and XRD and metallographic analyses were performed. The analysis results are as follows: Figure 3 and Figure 4 As shown. By Figure 3 It can be seen that the coatings obtained in Examples 1-3 of the present invention are mainly composed of austenite and ferrite phases. Figure 4 It can be seen that the coating obtained by the present invention has fine grains, ferrite in a skeleton shape, and AlN particles are dispersed.

[0077] Application examples

[0078] The application performance of the shell-breaking hammerheads strengthened in Examples 1-3 was tested. Example 1 involved strengthening 6 hammerheads, all of which were tested in a 400KA electrolytic cell in the second phase of an aluminum group's plant in Ningxia. Example 2 involved repairing and strengthening 6 hammerheads, all of which were tested in a 400KA electrolytic cell in an aluminum group's plant in Northwest China. Example 3 involved strengthening 12 hammerheads, 6 of which were tested in a 350KA electrolytic cell in an aluminum group's plant in Ningxia. The application performance of the shell-breaking hammerheads strengthened in each example is shown in Table 2 below.

[0079] Table 2

[0080]

[0081] 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 wear-resistant coating material, characterized in that, Includes the following steps: S1. Prepare raw material powder according to the following mass percentages: Ni: 15%~19%, Cr: 23%~27%, Al: 3%~6%, Si: 1%~2%, Si3N4: 2%~4%, with the balance being Fe. The total amount of each raw material is 100%. S2. Fe, Cr, Ni, Al and Si in the raw material powder are mixed and ball-milled to obtain alloyed powder; the alloyed powder is mixed with Si3N4 powder, a process control agent is added and wet milling is performed, the product is dried and sieved to obtain mixed powder; S3. Ethyl cellulose and turpentine percolate are mixed in a certain proportion to obtain an adhesive. The mixed powder and the adhesive are mixed in a certain proportion to obtain an alloy paste. S4. The alloy paste is melted onto the surface of the substrate to form a wear-resistant coating material.

2. The preparation method according to claim 1, characterized in that, In step S1, the mesh size of the raw material powder is 100~300 mesh.

3. The preparation method according to claim 1, characterized in that, In step S2, the ball milling process is carried out under a protective atmosphere, the ball milling speed is 280~300 rpm, and the ball milling time is 20~48 h.

4. The preparation method according to claim 1, characterized in that, In step S2, the process control agent for wet milling is selected from one or more combinations of anhydrous ethanol, deionized water, and n-hexane.

5. The preparation method according to claim 1, characterized in that, In step S2, the rotation speed of the wet grinding process is 280~300 rpm, and the wet grinding time is 2~4 hours.

6. The preparation method according to claim 1, characterized in that, Step S4 includes: applying the alloy paste with a thickness of 6-8 mm to the pretreated substrate surface to form an alloy paste surface layer, and drying it at 50-70°C; and using a plasma cladding method to clad the substrate with the alloy paste surface layer to form a wear-resistant coating material on the substrate surface.

7. The preparation method according to claim 6, characterized in that, In step S4, the parameters for plasma cladding include: the distance between the cladding gun tip and the surface of the alloy paste is 6~10mm, the cladding speed is 6~10mm / s, and the cladding current is 180~220A.

8. A method for strengthening the shell-breaking hammerhead of an electrolytic cell, characterized in that, The wear-resistant coating material is prepared on the surface of the shell-breaking hammer head using the preparation method described in claim 6.

9. The method according to claim 8, characterized in that, In the plasma cladding process of step S4, the cladding path is wrapped around the large cylindrical section of the hammer head, starting from the direction of the small cylindrical section of the hammer head, and after completing a full circle, it moves towards the far end with an overlap rate of 40%~60% to complete the preparation of the wear-resistant coating material on the surface of the shell-breaking hammer head.

10. A shell-breaking hammer for an electrolytic cell, characterized in that, The electrolytic cell shell-breaking hammer is obtained by strengthening according to the method described in claim 8 or 9.

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