A wear-resistant crust-breaking hammerhead for aluminum electrolysis and its preparation method

Abstract

This application relates to the field of preparation of aluminum electrolysis equipment, and particularly to a wear-resistant crust-breaking hammerhead for aluminum electrolysis and a preparation method thereof. The method includes: pretreating the surface of the steel to obtain a steel substrate with high surface activation energy; subjecting the steel substrate to surface titanium alloying to obtain a steel substrate with a surface alloy layer; performing carburizing treatment on the surface of the steel substrate with the surface alloy layer to obtain a hammerhead substrate with a TiC wear-resistant layer; processing the hammerhead substrate with the TiC wear-resistant layer and preparing a welding groove to obtain a wear-resistant crust-breaking hammerhead for aluminum electrolysis. The pretreatment is carried out by chemical treatment and physical treatment methods. The content of TiC hard phase in the TiC wear-resistant layer is ≥40%. By adopting a surface treatment method of titanium carburizing first and then carburizing, TiC hard phase is formed in-situ on the steel surface. This hard phase can achieve the effects of fine grain strengthening and dispersion strengthening by pinning dislocations and hindering grain boundary movement, greatly improving surface hardness and wear resistance.

Description

Technical Field

[0001] This application relates to the field of aluminum electrolysis equipment preparation, and particularly to a wear-resistant crust-breaking hammerhead for aluminum electrolysis and its preparation method. Background Art

[0002] At present, the alumina feeding of pre-baked electrolytic cells adopts automatic intermediate point feeding. Generally, each electrolytic cell is equipped with 3-6 crust-breaking hammerheads for alternate crust-breaking and feeding. The main principle is to control the crust-breaking cylinder and the striking hammerhead through a solenoid valve, so as to break the hard crust on the surface of the electrolyte and form a hole, which can be used as an alumina feeding point. This method can well realize the automatic control of alumina feeding. However, according to the process requirements, each crust-breaking hammerhead needs to strike about 1400 times per day and night, and each time the crust-breaking hammerhead has to rub against the crust layer and soak in the electrolyte for 2-3 seconds. The frequent crust-breaking action will cause great wear on the crust-breaking hammerhead, gradually forming a tapered shape, affecting the crust-breaking effect and the feeding amount. Therefore, it is necessary to carry out regular maintenance and replacement.

[0003] At present, the main component of the crust-breaking hammerhead on the market is Q235 steel. Its main advantages are low price and easy welding. At the same time, its disadvantages are also quite obvious. Generally, the service life of the crust-breaking hammerhead is only 3 months. Frequent replacement of the crust-breaking hammerhead will cause a large waste of resources.

[0004] At present, the methods for improving the wear resistance of aluminum electrolysis crust-breaking hammerheads mainly include integral melting and casting method, bimetal composite casting method, and wear-resistant coating method. However, due to the influence of welding performance, wear resistance, forming performance, etc., the improvement range of the wear resistance of the hammerhead is limited. Therefore, how to provide a method for improving the wear resistance of the crust-breaking hammerhead to improve its service life is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0005] This application provides a wear-resistant crust-breaking hammerhead for aluminum electrolysis and its preparation method to solve the technical problems of low wear resistance and low service life of the crust-breaking hammerhead in the prior art.

[0006] In the first aspect, this application provides a preparation method for a wear-resistant crust-breaking hammerhead for aluminum electrolysis, and the method includes:

[0007] Pretreat the surface of the steel to obtain a steel matrix with high surface activation energy;

[0008] Perform surface titanium alloying on the steel matrix to obtain a steel matrix with a surface alloy layer;

[0009] Perform carburizing treatment on the surface of the steel matrix with the surface alloy layer to obtain a hammerhead matrix with a Ti wear-resistant layer;

[0010] Process the said hammer head matrix containing TiC hard phase and prepare a welding groove to obtain a wear-resistant shell-breaking hammer head for aluminum electrolysis;

[0011] Among them, the said pretreatment includes pretreatment by chemical treatment and physical treatment methods;

[0012] The content of TiC hard phase in the said TiC wear-resistant layer is ≥40%.

[0013] Optionally, the said physical treatment includes shot peening treatment, the pressure of the said shot peening is 0.4 MPa to 2 MPa, and the time of the said shot peening is 10 min to 30 min.

[0014] Optionally, the diameter of the shot used for the said shot peening treatment is 1.0 mm to 1.5 mm, the mass of the shot used for the said shot peening treatment is 3.0 mg to 4.0 mg, and the spraying distance of the said shot peening treatment is 10 cm to 15 cm.

[0015] Optionally, the said titanium alloying includes titanium alloying by double glow plasma titanium implantation method, the target used for the said double glow plasma titanium implantation is a pure titanium target, and the purity of the said pure titanium target is ≥99.99%;

[0016] The reaction gas used for the said double glow plasma titanium implantation is pure argon gas, and the purity of the said pure argon gas is ≥99.99%.

[0017] Optionally, the source voltage of the said double glow plasma titanium implantation is 850 V to 950 V, the cathode voltage of the said double glow plasma titanium implantation is 300 V to 400 V, and the electrode spacing of the said double glow plasma titanium implantation is 10 mm to 20 mm.

[0018] Optionally, the temperature of the said double glow plasma titanium implantation is 1000 °C to 1050 °C, and the holding time of the said double glow plasma titanium implantation is 3 h to 5 h.

[0019] Optionally, the temperature of the said carburizing treatment is 850 °C to 950 °C, the time of the said carburizing treatment is 1 h to 10 h, and the carburizing pressure of the said carburizing treatment is 0.1 kPa to 2.0 kPa; and / or,

[0020] The carburizing medium of the said carburizing treatment includes at least one of methanol, kerosene, benzene and toluene, acetone, propane, butane, ethyl acetate, etc., isopropanol, natural gas and liquefied petroleum gas.

[0021] Optionally, the said carburizing treatment includes strong carburizing treatment and diffusion carburizing treatment, the temperature of the said strong carburizing treatment is 900 °C to 950 °C, and the time of the said strong carburizing treatment is 0.5 h to 3 h;

[0022] The temperature of the diffusion carburizing treatment is 900°C to 950°C, and the time of the diffusion carburizing is 0.5 h to 2 h.

[0023] Optionally, the carburizing treatment further includes gas quenching treatment. The temperature of the gas quenching treatment is 850°C to 950°C, the pressure of the gas quenching treatment is 0.5 MPa to 1.5 MPa, and the cooling gas for the gas quenching treatment includes nitrogen and / or argon.

[0024] In a second aspect, the present application provides a wear-resistant crust-breaking hammerhead for aluminum electrolysis. The crust-breaking hammerhead is prepared by the preparation method described in the first aspect. The crust-breaking hammerhead sequentially includes a steel matrix and a TiC wear-resistant layer from the inside to the outside.

[0025] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0026] A preparation method of a wear-resistant crust-breaking hammerhead for aluminum electrolysis provided by an embodiment of the present application pre-treats on the steel matrix of a traditional crust-breaking hammerhead, and at the same time defines that the pre-treatment includes chemical treatment and physical treatment to increase the surface roughness of the steel matrix. Then, combined with titanium alloying and carburizing treatment, a stable TiC wear-resistant layer is formed on the surface of the steel matrix. There is a TiC hard phase in the wear-resistant layer, and the specific content of the TiC hard phase is controlled. The TiC hard phase can achieve the effects of fine grain strengthening and dispersion strengthening by pinning dislocations and hindering grain boundary movement. Therefore, sufficient TiC hard phase can greatly improve the surface hardness and wear resistance of the crust-breaking hammerhead. At the same time, the TiC hard phase can be tightly combined with the steel matrix, and the bonding strength is high, thereby increasing the service life of the crust-breaking hammerhead. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings here are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic flow chart of a preparation method of a wear-resistant crust-breaking hammerhead for aluminum electrolysis provided by an embodiment of the present application;

[0030] Figure 2 It is a schematic structural diagram of a wear-resistant crust-breaking hammerhead for aluminum electrolysis provided by an embodiment of the present application;

[0031] Among them, 1 - steel matrix, 2 - TiC wear-resistant layer. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0033] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, equipment, etc. used in the present application can be obtained through market purchase or can be prepared by existing methods.

[0034] The creative concept of the present application is as follows:

[0035] Frequent replacement of the cell shell breaking hammers will result in a waste of a large amount of resources, which is mainly manifested as follows:

[0036] (1) Waste of material resources. For example, a 320 kA electrolysis workshop has 288 electrolytic cells, each electrolytic cell is equipped with 5 cell shell breaking hammers, and each hammer weighs about 15 kg. The one-time replacement of cell shell breaking hammers is: 5 pieces × 288 pieces = 1440 pieces. The cell shell breaking hammers need to be replaced 4 times a year, and a total of 5760 hammers are required, with a total tonnage of about 86.4 tons, resulting in a large consumption of raw materials for preparing the steel of the cell shell breaking hammers;

[0037] (2) Waste of human resources. The disassembly and replacement of the hammers waste a large amount of labor. For 320 kA, when disassembling the worn hammers, new hammers also need to be installed. The total amount of steel in the process of disassembling and installing the hammers is about 86.4 tons, resulting in a large labor intensity for maintenance personnel, and batch replacement of the hammers also affects normal production;

[0038] (3) Affect the quality of electrolytic aluminum. The cell shell breaking hammers are worn and melted into the electrolytic aluminum ingots, increasing the impurity content of the electrolytic aluminum ingots and reducing the quality of the aluminum ingots.

[0039] Currently, the methods for improving the wear resistance of the cell shell breaking hammers in aluminum electrolysis include:

[0040] (1) Using the lost foam casting or sand casting process to prepare hammers made of ferroalloy materials. By controlling the content of alloy elements such as manganese and chromium, the wear resistance of the hammers is increased, and the replacement cycle is extended;

[0041] (2) The material is used for smelting, producing steel ingots, forging or hot rolling, segmenting, heat treatment, machining and forming, etc. to make a cell breaking hammer head. Under the cooperation of the traditional austenitic stainless steel production process, the hammer head will form an austenitic stainless steel matrix of the Cr-Ni type with high temperature resistance and electrochemical corrosion resistance. At the same time, due to the presence of tungsten element, tungsten carbide precipitation phases enter the austenitic stainless steel matrix to form a tungsten carbide precipitation phase skeleton with high creep resistance and high wear resistance and are dispersed in the cell breaking hammer head material, significantly improving the hardness, high creep resistance and high wear resistance of the cell breaking hammer head material.

[0042] (3) Design a new cell breaking hammer head. The hammer head includes a hammer head part and a mounting part. The mounting part includes a thread connection section, a transition cone section and a hammer head connection section which are integrally formed. One end of the hammer head part is movably connected to the hammer head connection section, and the other end is hemispherical. The hammer head part includes a hammer head matrix and a carburized layer, a boronized layer and an anti-corrosion layer which are sequentially arranged on the outer surface of the hammer head matrix, thereby improving the wear resistance of the hammer head.

[0043] (4) Using the method of bimetallic composite casting, with the Fe-Cr-Mn-C-B alloy as the cell breaking hammer head and the ZG25CrMnSi low alloy high strength steel with excellent welding performance as the hammer handle, the two materials are compounded together by casting, effectively improving the service life of the cell breaking hammer head.

[0044] (5) First, pretreat the surface of the Q235 steel hammer head, then use methods such as plasma surfacing to melt and deposit a high-performance coating on the surface of the Q235 steel hammer head, and finally perform heat treatment on it to make it have the characteristics of high hardness, high wear resistance and high corrosion resistance.

[0045] (6) Design a new cell breaking hammer head material. This material has comprehensive material properties integrating high wear resistance, anti-electrochemical corrosion and high temperature oxidation resistance. The service life of the cell breaking hammer head produced by using this material reaches more than 12 months. Compared with the service life of similar hammer heads ranging from 2 to 9 months, the life is increased by 1.3 to 6 times.

[0046] However, the cell breaking hammer heads obtained by the above technologies are affected by aspects such as welding performance, wear resistance, and forming performance, and the improvement range of the wear resistance of the hammer heads is limited. Therefore, how to provide a method to improve the wear resistance of the cell breaking hammer head to improve the service life of the cell breaking hammer head is a technical problem that needs to be solved urgently at present.

[0047] As Figure 1 shown, the embodiment of the present application provides a preparation method for a wear-resistant cell breaking hammer head for aluminum electrolysis. The method includes:

[0048] S1. Pretreat the surface of the steel to obtain a steel matrix with high surface activation energy;

[0049] S2. Perform surface titanium alloying on the steel substrate to obtain a steel substrate with a surface alloy layer;

[0050] S3. Perform carburizing treatment on the surface of the steel substrate with the surface alloy layer to obtain a hammer head substrate with a TiC wear-resistant layer;

[0051] S4. Process the hammer head substrate containing the TiC hard phase and prepare a welding groove to obtain a wear-resistant shell-breaking hammer head for aluminum electrolysis;

[0052] Among them, the pretreatment includes pretreatment by chemical treatment and physical treatment methods;

[0053] The content of TiC hard phase in the TiC wear-resistant layer is ≥40%.

[0054] In the embodiments of the present application, by introducing chemical treatment to remove stains, scale, etc. on the steel surface, and then using physical treatment to increase the surface roughness of the steel, thereby increasing the activation energy of the steel surface and improving the bonding strength between the subsequent TiC hard phase and the steel, so as to improve the service life of the shell-breaking hammer head.

[0055] Control the specific content of the TiC hard phase. Since the TiC hard phase can pin dislocations and hinder grain boundary movement to achieve the effects of fine grain strengthening and dispersion strengthening, sufficient TiC hard phase can greatly improve the surface hardness and wear resistance of the shell-breaking hammer head.

[0056] The steel can be Q235 steel or other steels used for hammer heads.

[0057] In some optional embodiments, the physical treatment includes shot peening treatment, the pressure of the shot peening is 0.4 MPa to 2 MPa, and the time of the shot peening is 10 min to 30 min.

[0058] In the embodiments of the present application, controlling the physical treatment to include shot peening treatment and controlling the pressure and time of the shot peening treatment can increase the surface roughness of the steel by shot peening, change the flat state of the steel surface to a gully state, so that more active carbon atoms can be adsorbed on the surface during the carburizing process, gather enough active carbon atoms in a short time, form a carbon concentration difference, and the shot peening promotes plastic deformation on the surface layer of the material, the surface layer grains are refined, the dislocation density increases, and the lattice distortion increases, forming a large number of crystal defects. These crystal defects are the "highways" inside the material, making the active carbon atoms diffuse faster and deeper into the interior, thereby increasing the bonding strength between the subsequent TiC hard phase and the steel substrate.

[0059] In some alternative embodiments, the diameter of the shot used for shot peening is 1.0 mm to 1.5 mm, the mass of the shot used for shot peening is 3.0 mg to 4.0 mg, and the spraying distance of the shot peening is 10 cm to 15 cm.

[0060] In the embodiments of the present application, by controlling the specific shot and spraying distance used for shot peening, the roughness of the steel surface can be further made to meet the expectations, so that the surface hardness can be significantly increased during subsequent gas carburizing, and the hardness gradient from the surface to the inside decreases more gently, the brittleness of the carburized layer is reduced, the effective hardened layer depth is significantly increased, and the gas carburizing efficiency is improved.

[0061] In some alternative embodiments, the titanium alloying includes titanium alloying by means of double glow plasma titanium implantation. The target used for double glow plasma titanium implantation is a pure titanium target, and the purity of the pure titanium target is ≥99.99%;

[0062] The reaction gas used for double glow plasma titanium implantation is pure argon gas, and the purity of the pure argon gas is ≥99.99%.

[0063] In the embodiments of the present application, by controlling the specific method of titanium alloying, since double glow plasma surface titanium implantation does not go through the solidification process, and the carburizing temperature is relatively low, the diffusion rate of titanium is small, and the formed crystal nuclei are not easy to grow. Therefore, the formation of coarse eutectic TiC phase can be avoided, and thus fine and uniformly dispersed TiC hard phases can be formed after carburizing treatment.

[0064] By controlling the purity of the target and reaction gas for titanium alloying, the double glow plasma surface titanium implantation process can be made sufficient, which is convenient for forming a TiC wear-resistant layer with uniform thickness in the later stage.

[0065] In some alternative embodiments, the source voltage of the double glow plasma titanium implantation is 850 V to 950 V, the cathode voltage of the double glow plasma titanium implantation is 300 V to 400 V, and the electrode spacing of the double glow plasma titanium implantation is 10 mm to 20 mm.

[0066] In the embodiments of the present application, by controlling the specific parameters of double glow plasma titanium implantation, the diffusion rate of titanium can be made smaller, and the formed crystal nuclei are not easy to grow. Therefore, the formation of coarse eutectic TiC phase can be avoided.

[0067] In some alternative embodiments, the temperature of the double glow plasma titanium implantation is 1000 °C to 1050 °C, and the holding time of the double glow plasma titanium implantation is 3 h to 5 h.

[0068] In the embodiments of the present application, by controlling the specific temperature and specific holding time for double glow plasma titanium carburization, the temperature during the titanium carburization process can be relatively low, and the diffusion rate of titanium is small, so that the formed crystal nuclei are not prone to grow, thus avoiding the formation of coarse eutectic TiC phase and forming fine and uniformly dispersed TiC hard phases instead.

[0069] In some alternative embodiments, the temperature of the carburizing treatment is 850°C to 950°C, the time of the carburizing treatment is 1 h to 10 h, and the carburizing pressure of the carburizing treatment is 0.1 kPa to 2.0 kPa; and / or,

[0070] The carburizing medium for the carburizing treatment includes at least one of methanol, kerosene, benzene, toluene, acetone, propane, butane, ethyl acetate, isopropanol, natural gas, and liquefied petroleum gas.

[0071] In the embodiments of the present application, by controlling the specific process parameters of the carburizing treatment and the carburizing medium, since the carburizing temperature is lower than the titanium carburization temperature at this time, there is a chemical driving force for the precipitation of Ti atoms, and coupled with the large diffusion ability of carbon, the nucleation rate of TiC is high, so that fine and uniformly dispersed TiC hard phases can be formed with the participation of the carburizing medium.

[0072] To ensure the carbon potential, nitrogen or argon can also be added to the carburizing medium.

[0073] In some alternative embodiments, the carburizing treatment includes a strong carburizing treatment and a diffusion carburizing treatment. The temperature of the strong carburizing treatment is 900°C to 950°C, and the time of the strong carburizing treatment is 0.5 h to 3 h;

[0074] The temperature of the diffusion carburizing treatment is 900°C to 950°C, and the time of the diffusion carburizing is 0.5 h to 2 h.

[0075] In the embodiments of the present application, by controlling the specific parameters of the strong carburizing treatment and the diffusion carburizing treatment, a sufficient number of TiC hard phases can be formed on the surface of the steel matrix after titanium alloying.

[0076] The carbon potential of the strong carburizing treatment is controlled at 1.1%, and the carbon potential of the diffusion carburizing treatment is controlled at 0.8%.

[0077] In some alternative embodiments, the carburizing treatment further includes a gas quenching treatment. The temperature of the gas quenching treatment is 850°C to 950°C, the pressure of the gas quenching treatment is 0.5 MPa to 1.5 MPa, and the cooling gas for the gas quenching treatment includes nitrogen and / or argon.

[0078] In the embodiments of the present application, the specific process conditions for gas quenching treatment in carburizing treatment are controlled. Since titanium is a strong carbide-forming element and has a stronger affinity for carbon than iron, it will react with carbon preferentially and form TiC hard phases. These hard phases can pin dislocations and hinder grain boundary movement to achieve the effects of fine grain strengthening and dispersion strengthening, greatly improving the surface hardness and wear resistance of the shell-breaking hammer head.

[0079] Based on a general inventive concept, as Figure 2 shown, the present application provides a wear-resistant shell-breaking hammer head for aluminum electrolysis. The shell-breaking hammer head is prepared by the preparation method, and the shell-breaking hammer head includes a steel matrix 1 and a TiC wear-resistant layer 2 from inside to outside in sequence.

[0080] This shell-breaking hammer head is realized based on the above preparation method. The specific steps of the preparation method can refer to the above embodiments. Since this shell-breaking hammer head adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0081] In some optional embodiments, as shown in Table 1, the stability degree of carbides in the material of the shell-breaking hammer head from strong to weak is Hf > Zr > Ti > Ta > Nb > V > W > Mo > Cr > Mn > Fe.

[0082] Further, as shown in Table 1, the order of the stability of carbides from weak to strong is: Fe3C, M 23 C6, M6C, M2C, MC. Since the higher the hardness and melting point of the carbide, the stronger its stability, especially for MeX-type and Me2X-type carbides with a melting point of about 3000 °C, TiC not only has high hardness and high melting point, but also has high stability, and is suitable for applications in the high-temperature, wear-resistant, and corrosive environment of aluminum electrolysis.

[0083] Table 1 Distribution table of hardness and melting point of pure metals and carbides in the shell-breaking hammer head

[0084] Pure metal Ti Nb Zr V Mo W Cr α-Fe Hardness (HV) 230 300 300 140 350 400 220 80 Carbide TiC NbC ZrC VC <![CDATA[Mo2C]]> WC <![CDATA[Cr 23 C6]]> <![CDATA[Fe3C]]> Hardness (HV) 3200 2055 2840 2094 1480 1730 1650 860 Melting point (°C) 3140 3480 3350 2830 2410 2755 1580 1650

[0085] The following further elaborates the present application in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions noted in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0086] Example 1

[0087] First, pre-treat the surface of Q235 steel. Select the method of chemical cleaning to remove the oil stain on the surface of Q235 steel, and then perform shot peening on its surface. The diameter of the shot used for shot peening is 1.2 mm, the mass of the shot is 3.5 mg, the distance between the specimen and the nozzle is 12 cm, the shot peening pressure is 0.6 MPa, and the shot peening time is 30 min.

[0088] Adopt the method of double glow plasma titanium penetration on the pre-treated Q235 steel to carry out surface titanium alloying, forming a surface alloy layer with a relatively high Ti content; the target material used for double glow plasma titanium penetration is a pure titanium target with a purity ≥ 99.99%, and the reaction gas for double glow plasma titanium penetration is high-purity argon with a purity ≥ 99.99%, and the flow rate is 95 mL / min. The process conditions for titanium penetration are: the source electrode voltage is 880 V, the cathode voltage is 350 V, the electrode spacing is 15 mm, the temperature is 1020 °C, and the heat preservation time is 3 h. The effective thickness of the surface titanium penetration layer obtained is 100 μm.

[0089] Carry out carburizing treatment on the Q235 steel with surface titanium alloying, and in-situ react to generate disperse TiC hard phases; the carburizing medium is methanol, and its carburizing process is: first perform strong carburizing at 910 °C for 3 h, with a carbon potential of 1.1%; then perform diffusion carburizing at 910 °C for 2 h, with a carbon potential of 0.8%; after diffusion carburizing, cool down to 860 °C, with a carbon potential of 0.8%, and keep warm for 1 h. The proportion of TiC hard phases is 42%.

[0090] Adopt the method of machining to turn one end of the hammer head to prepare a welding groove, and obtain an aluminum electrolysis crust breaking hammer head.

[0091] The surface hardness of the aluminum electrolysis wear-resistant crust breaking hammer head after titanium alloying + carburizing treatment reaches 1123 HV 0.01 , and its service life in the electrolytic cell is 36 months.

[0092] Example 2

[0093] Compare Example 2 with Example 1. The differences between Example 2 and Example 1 are as follows:

[0094] First, pre-treat the surface of Q235 steel. Select the method of chemical cleaning to remove the oil stain on the surface of Q235 steel, and then perform shot peening on its surface. The diameter of the shot used for shot peening is 1.0 mm, the mass of the shot is 3.2 mg, the distance between the specimen and the nozzle is 10 cm, the shot peening pressure is 0.6 MPa, and the shot peening time is 30 min.

[0095] The surface of the pretreated Q235 steel is subjected to surface titanium alloying by double glow plasma titanium penetration to form a surface alloy layer with a relatively high Ti content. The target used is a pure titanium target with a purity of ≥99.99%, and the reaction gas is high-purity argon with a purity of ≥99.99% and a flow rate of 98 ml / min. The titanium penetration process conditions are as follows: source electrode voltage 880 V, cathode voltage 360 V, electrode spacing 15 mm, temperature 1010 °C, heat preservation for 3 h, and the effective thickness of the surface titanium penetration layer obtained is 120 μm.

[0096] The surface titanium alloyed Q235 steel is subjected to carburizing treatment to in-situ react and generate disperse TiC hard phases. The carburizing medium is methanol, and its carburizing process is as follows: first, perform strong carburizing at 900 °C for 3 h with a carbon potential of 1.1%; then perform diffusion carburizing at 900 °C for 2 h with a carbon potential of 0.8%; after diffusion carburizing, cool down to 880 °C with a carbon potential of 0.8% and keep it warm for 1 h, and the proportion of TiC hard phases is 41%.

[0097] By means of machining, one end of the hammer head is turned to prepare a welding groove, and an aluminum electrolysis crust breaking hammer head is obtained.

[0098] The surface hardness of the aluminum electrolysis wear-resistant crust breaking hammer head after titanium alloying + carburizing treatment reaches 1110 HV 0.01 and its service life in the electrolytic cell is 38 months.

[0099] Example 3

[0100] Compare Example 3 with Example 1. The differences between Example 3 and Example 1 are as follows:

[0101] First, the surface of the Q235 steel is pretreated. The chemical cleaning method is used to remove the oil stains on the surface of the Q235 steel, and then shot peening treatment is carried out on its surface. The diameter of the shot used for shot peening is 1.4 mm, the mass of the shot is 3.8 mg, the distance between the specimen and the nozzle is 13 cm, the shot peening pressure is 0.8 MPa, and the shot peening time is 30 min.

[0102] The surface of the pretreated Q235 steel is subjected to surface titanium alloying by double glow plasma titanium penetration to form a surface alloy layer with a relatively high Ti content. The target used is a pure titanium target with a purity of ≥99.99%, and the reaction gas is high-purity argon with a purity of ≥99.99% and a flow rate of 98 ml / min. The titanium penetration process conditions are as follows: source electrode voltage 880 V, cathode voltage 360 V, electrode spacing 15 mm, temperature 1040 °C, heat preservation for 3 h, and the effective thickness of the surface titanium penetration layer obtained is 120 μm.

[0103] Carburize the Q235 steel with surface titanium alloying to in-situ react and generate disperse TiC hard phases; the carburizing medium is methanol, and its carburizing process is as follows: first perform strong carburization at 915°C for 3 h with a carbon potential of 1.1%; then perform diffusion carburization at 915°C for 2 h with a carbon potential of 0.8%; after diffusion carburization, cool down to 880°C with a carbon potential of 0.8% and hold for 1 h, and the proportion of TiC hard phases is 45%.

[0104] By means of machining, turn one end of the hammer head to prepare a welding groove to obtain an aluminum electrolysis crust breaking hammer head.

[0105] The surface hardness of the aluminum electrolysis wear-resistant crust breaking hammer head after titanium alloying + carburizing treatment reaches 1250 HV 0.01 , and its service life in the electrolytic cell is 46 months.

[0106] One or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages:

[0107] (1) The embodiments of the present application provide a preparation method for a wear-resistant crust breaking hammer head for aluminum electrolysis. By adopting a surface treatment method of first titaniumizing and then carburizing, TiC hard phases are formed in-situ on the surface of Q235 steel. These hard phases can pin dislocations and hinder grain boundary movement to achieve the effects of fine grain strengthening and dispersion strengthening, greatly improving surface hardness and wear resistance.

[0108] (2) The embodiments of the present application provide a preparation method for a wear-resistant crust breaking hammer head for aluminum electrolysis. The content of TiC hard phases in the TiC wear-resistant layer is high and forms a metallurgical bond with the steel matrix. The bonding strength of this method is high, and there is no cracking or spalling phenomenon during long-term use.

[0109] (3) The embodiments of the present application provide a preparation method for a wear-resistant crust breaking hammer head for aluminum electrolysis. Since double glow plasma surface titaniumizing does not go through the solidification process and the carburizing temperature is relatively low, the diffusion rate of titanium is small, and the formed crystal nuclei are not easy to grow. Therefore, the formation of coarse eutectic TiC phases is avoided, but fine, uniform and disperse TiC hard phases are formed.

[0110] (4) The embodiments of the present application provide a preparation method for a wear-resistant crust breaking hammer head for aluminum electrolysis. Since the carburizing temperature is lower than the titaniumizing temperature, Ti atoms have a chemical driving force for precipitation, and coupled with the large diffusion ability of carbon, the nucleation rate of TiC is high, and the proportion of TiC hard phases ≥ 40%.

[0111] (5) The embodiments of the present application provide a wear-resistant crust breaking hammer head for aluminum electrolysis, whose surface hardness can reach 1100 HV 0.01 As above, the wear resistance is more than 20 times that of ordinary hammer heads, which can effectively extend the service life of the crust breaking hammer head, reduce the usage amount of hammer heads, reduce the Fe impurity content in primary aluminum, improve production efficiency, reduce labor intensity, and lower production costs.

[0112] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0113] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing direction in the drawings. Additionally, in the description of the specification of the present application, the terms "comprising", "including", etc. mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the associated relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B may be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following (items)" or similar expressions refer to any combination of these items, including any combination of single item (s) or plural item (s). For example, "at least one of (item) a, b, or c", or, "at least one of (item) a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0114] The above description is only the specific implementation manners of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A preparation method of a wear-resistant crust-breaking hammerhead for aluminum electrolysis, characterized in that The method includes: Pre-treating the surface of the steel to obtain a steel substrate with a high surface activation energy; Performing surface titanium alloying on the steel substrate to obtain a steel substrate with a surface alloy layer; Performing carburizing treatment on the surface of the steel substrate with the surface alloy layer to obtain a hammer head substrate with a TiC wear-resistant layer; Processing the hammer head substrate with the TiC wear-resistant layer and preparing a welding groove to obtain a wear-resistant crust-breaking hammer head for aluminum electrolysis; Among them, the pre-treatment includes pre-treatment by chemical treatment and physical treatment methods; The steel is Q235 steel, the content of TiC hard phase in the TiC wear-resistant layer is ≥ 40%, and the surface hardness of the wear-resistant cell-breaking hammerhead for aluminum electrolysis is 1100 HV 0.01 or above; Titanium alloying is carried out by double glow plasma titanium penetration. The source voltage of the double glow plasma titanium penetration is 850V - 950V, the cathode voltage is 300V - 400V, the electrode spacing is 10mm - 20mm, the temperature is 1000°C - 1050°C, and the holding time is 3h - 5h; The carburizing treatment includes strong carburizing treatment and diffusion carburizing treatment. The temperature of the strong carburizing treatment is 900°C - 950°C, and the time is 0.5h - 3h; The temperature of the diffusion carburizing treatment is 900°C - 950°C, and the time is 0.5h - 2h; The carbon potential of the strong carburizing treatment is controlled at 1.1%, and the carbon potential of the diffusion carburizing treatment is controlled at 0.8%; The target material used for the double glow plasma titanium penetration is a pure titanium target material, and the reaction gas used is pure argon gas. The purity of the pure titanium target material is ≥99.99%, and the purity of the pure argon gas is ≥99.99%; The carburizing medium for the carburizing treatment includes at least one of methanol, kerosene, benzene, toluene, acetone, propane, butane, ethyl acetate, isopropyl alcohol, natural gas, and liquefied petroleum gas.

2. The preparation method according to claim 1, characterized in that, The physical treatment includes shot peening treatment. The pressure of the shot peening is 0.4MPa - 2MPa, and the time of the shot peening is 10min - 30min.

3. The preparation method according to claim 2, characterized in that, The diameter of the shot used for the shot peening treatment is 1.0mm - 1.5mm, the mass of the shot used for the shot peening treatment is 3.0mg - 4.0mg, and the spraying distance of the shot peening treatment is 10cm - 15cm.

4. The preparation method according to claim 1, wherein The carburizing treatment further includes gas quenching treatment. The temperature of the gas quenching treatment is 850°C - 950°C, the pressure of the gas quenching treatment is 0.5MPa - 1.5MPa, and the cooling gas for the gas quenching treatment includes nitrogen and / or argon.

5. A wear-resistant crust-breaking hammer head for aluminum electrolysis, characterized in that, The crust-breaking hammer head is prepared by the preparation method described in any one of claims 1 - 4. The crust-breaking hammer head includes a steel substrate and a TiC wear-resistant layer from the inside to the outside in sequence.

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