An electrode coating for improving low-temperature arc striking performance and a preparation method thereof

Abstract

The application discloses a welding rod coating for improving low-temperature arc striking performance and a preparation method thereof, and belongs to the technical field of welding materials. The method comprises the following steps: taking microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate and anhydrous borax, mixing them uniformly to obtain a template premixing powder; in a stirring state, adding a silicate diluent to the template premixing powder in a spraying mode, drying, crushing and sieving to obtain a composite pore-forming agent; mixing the composite pore-forming agent with a coating base powder uniformly to obtain a coating dry powder, adding a water glass solution and stirring uniformly to obtain a coating wet material; coating the coating wet material on the surface of a welding core, and drying, grinding the mouth and baking to obtain the welding rod coating. The welding rod coating can improve the one-time arc striking success rate in a low-temperature environment, shorten the average arc striking time, reduce the sticking rate, and improve the arc striking stability after re-arc striking and low-temperature storage and transportation.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to a welding electrode coating for improving low-temperature arc ignition performance and its preparation method. Background Technology

[0002] Low-hydrogen basic welding electrodes are widely used in welding critical load-bearing structures such as bridges, pressure vessels, ships, offshore platforms, low-temperature steel structures, and field pipelines due to their low diffusible hydrogen content, good crack resistance, and high low-temperature impact toughness. These electrodes typically use alkaline minerals such as marble and fluorite as the main components of their coating. By forming an alkaline slag and a low-hydrogen protective atmosphere, they reduce the diffusible hydrogen content in the weld metal, thereby improving the crack resistance and low-temperature service reliability of the weld joint.

[0003] However, low-hydrogen basic welding electrodes generally suffer from insufficient arc-starting performance in practical applications, especially in low-temperature construction environments ranging from -20℃ to -40℃. This problem is mainly manifested in a decreased success rate of arc ignition on the first attempt, easy adhesion of the electrode tip to the workpiece, arc instability during the short arc phase, and difficulty in re-igniting the arc after it is extinguished midway through welding. For outdoor steel structure installation, winter pipeline construction, and emergency repair welding in low-temperature environments, the difficulty in arc ignition not only reduces construction efficiency but may also cause damage to the electrode tip coating, increased porosity at the arc ignition point, and fluctuations in joint quality due to repeated scratching for arc ignition.

[0004] Analysis of the arc ignition process reveals that the difficulty in low-temperature arc ignition is not simply due to the high ionization potential of a single coating mineral, but rather determined by the coating composition, the microstructure of the electrode tip, the initial conduction path, and the arc establishment process. Specifically: on the one hand, low-hydrogen alkaline welding electrodes have a high content of alkaline minerals such as marble and fluorite in their coatings, making it difficult to quickly provide sufficient conductive and ionizing particles in a cold state; on the other hand, the low-temperature environment deteriorates the contact state between the core tip, the coating end face, and the workpiece, making it difficult to form a stable partial discharge channel during the initial short-circuit-separation stage. Furthermore, conventional arc-stabilizing components only fully function after the arc has been established and reached a relatively high temperature, offering limited assistance for cold-state conduction and local pre-ionization in the initial stage of arc ignition.

[0005] In existing technologies, to improve the arc-starting performance of alkaline welding electrodes, methods such as increasing the content of arc stabilizer in the coating, adding conductive powder, adjusting the water glass binder system, or adding an additional arc-starting agent layer at the arc-starting end of the electrode are commonly used. For example, Chinese invention patent CN115635213B discloses an arc-starting agent for welding electrodes. This solution does not directly change the electrode coating itself, but rather coats an external arc-starting agent onto the core end face of the arc-starting end of the alkaline welding electrode. This arc-starting agent includes a mixed powder and a potassium-sodium water glass binder. The mixed powder contains components such as copper powder, graphite, aluminum-magnesium alloy, manganese dioxide, cotton, sodium alginate, potassium titanate, and atomized iron powder. The potassium-sodium water glass is mixed with the mixed powder in a certain proportion and then coated onto the end of the welding electrode, and then baked and cured to form an arc-starting auxiliary layer.

[0006] The aforementioned method of applying an external arc-starting agent to the electrode tip can improve the initial arc-starting performance of the electrode to a certain extent and has practical value. However, this method still has the following shortcomings: First, applying an external arc-starting agent requires adding an end coating and baking process after the electrode is formed, which increases the production cycle, equipment configuration, and quality control difficulty; Second, the external coating mainly relies on the interface adhesion with the end face of the core or the end of the coating to maintain stability, and there is a risk of damage, peeling, or local failure after low-temperature storage and transportation, handling collisions, end wear, or long-term storage; Third, this method mainly targets the initial arc-starting at the initial end of the electrode, and has limited improvement on re-arcing after the arc is extinguished during welding; Fourth, the external arc-starting agent and the coating body are usually in a localized adhesion relationship, which is difficult to change the problem of random dispersion of functional components inside the coating body and the lack of continuous conductive paths in the discharge micro-region.

[0007] In addition, some technical solutions attempt to directly add conductive powder, arc-stabilizing powder, fluxing powder, or dielectric powder to the electrode coating to improve the overall conductivity and arc stability of the coating. However, if these functional powders are simply randomly dispersed in the coating using ordinary dry mixing methods, their actual effective location is uncontrollable, making it difficult to ensure that the functional powders are concentrated near the orifice, orifice wall, and core tip where local discharge actually occurs at the moment of arc ignition. Especially under low-temperature conditions, the arc ignition process occurs in an extremely short time and within an extremely small micro-region. Even if the overall content of randomly dispersed functional powders is high, it may not be able to form a continuous and effective synergistic effect of conduction, polarization, and arc stabilization near the initial discharge channel. Excessive addition of conductive powder or arc-stabilizing powder may also affect the coating's formability, slag fluidity, weld metallurgical properties, and low-hydrogen characteristics.

[0008] Therefore, existing technologies still require a new electrode coating and its preparation method that does not rely on an additional external arc-starting agent layer, but instead constructs a functionalized microstructure within the coating body that can participate in the low-temperature arc-starting process. This allows conductive, dielectric, low-temperature liquid-phase bridging, and high-temperature arc-stabilizing components to accumulate and distribute near the arc-starting end orifice and orifice wall, forming a continuous and synergistic channel from cold pre-conduction to stable arc combustion. This improves the stability of primary arc-starting, re-arc-starting, and arc-starting after low-temperature storage and transportation in low-temperature environments. Summary of the Invention

[0009] The purpose of this invention is to provide a welding electrode coating and its preparation method that improves the low-temperature arc ignition performance, thereby increasing the success rate of arc ignition in a single operation at low temperatures, shortening the average arc ignition time, reducing the electrode sticking rate, and improving the arc ignition stability after re-ignition and low-temperature storage and transportation.

[0010] The objective of this invention can be achieved through the following technical solutions:

[0011] A method for preparing a welding electrode coating that improves low-temperature arc ignition performance includes the following steps: S1. Mix microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax evenly to obtain template premix powder; add silicate diluent to the template premix powder by spraying while stirring, so that aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax are anchored to the surface of microcrystalline cellulose through silicate solid phase; after drying, crushing, and sieving, obtain composite pore-forming agent. S2. Mix the composite pore-forming agent with the drug coating base powder evenly to obtain dry drug coating powder, add water glass solution and stir evenly to obtain wet drug coating material; S3. The wet flux is pressed onto the surface of the welding core, and after drying, grinding and baking, the flux coating of the welding electrode is obtained.

[0012] Aluminum-doped zinc oxide, cerium oxide, barium titanate, and borax are anchored to the surface of microcrystalline cellulose via silicate solid phases. Microcrystalline cellulose acts as a sacrificial template, forming porous channels during subsequent baking and welding heating. This allows the enriched aluminum-doped zinc oxide, cerium oxide, barium titanate, borates, and silicate solid phases to accumulate near the pore walls. Aluminum-doped zinc oxide is used to form initial micro-conduction under low temperature and high electric field conditions. Barium titanate can form dielectric polarization regions, enhancing the local electric field at the orifice. Borax softens or forms a low-temperature liquid phase in the early heating stage, acting as a bridge. Cerium oxide is located near the discharge and melting micro-regions, playing a role in stabilizing the arc and improving metallurgy after the arc is established. This transforms the originally randomly dispersed functional powder into continuous functional channels distributed along the pore walls, thereby reducing the conduction threshold in the early stage of low-temperature arc ignition.

[0013] The silicate diluent provides silicates as an anchoring medium. After spraying, potassium silicate and sodium silicate form a silicate solid phase during the drying process, which fixes aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax on the surface of microcrystalline cellulose. Potassium ions in potassium silicate have low ionization energy, which improves arc stability. Sodium ions in sodium silicate are more conducive to bonding, curing, and forming inorganic connection phases, thus balancing arc stability and forming.

[0014] As a preferred embodiment of the present invention, in step S1, the silicate diluent is composed of potassium silicate, sodium silicate and deionized water in a mass ratio of 0.2-0.8:1:12-24; the mass ratio of microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate and anhydrous borax is 35-50:18-32:8-18:6-16:6-18.

[0015] As a preferred embodiment of the present invention, in step S2, the mass ratio of the composite pore-forming agent, the coating base powder, and the water glass solution is 2.5-4.5:95.5-97.5:24-28; the coating base powder is composed of marble powder, fluorite powder, rutile titanium dioxide, medium carbon manganese iron powder, ferrosilicon powder, regulator, and iron powder in a mass ratio of 34-38:15-19:8-10:7-10:3-5:10-15:10-16.

[0016] The flux base powder is composed of marble powder, fluorite powder, rutile titanium dioxide, medium-carbon ferromanganese powder, ferrosilicon powder, a modifier, and iron powder, which can maintain the basic welding performance of low-hydrogen basic electrodes. Marble powder and fluorite powder form the basic alkaline slag system, which helps reduce diffusible hydrogen in the weld and ensures the weld's crack resistance; rutile titanium dioxide improves arc stability and slag coverage; medium-carbon ferromanganese powder and ferrosilicon powder are used for deoxidation and alloy transition; iron powder helps improve deposition efficiency and arc stability; and the modifier is used to adjust the wet coating properties, slag viscosity, coverage, and slag removal. While achieving good performance of low-hydrogen basic electrodes, a small amount of composite pore-forming agent is introduced to achieve targeted improvement in low-temperature arc ignition performance.

[0017] As a preferred embodiment of the present invention, the regulator includes one or more of quartz powder, mica powder, kaolin and potassium feldspar powder.

[0018] As a preferred embodiment of the present invention, the regulator is composed of quartz powder, mica powder, kaolin and potassium feldspar powder in a mass ratio of 3-8:1-4:1-4:2-6.

[0019] Quartz powder is used to adjust the acid-base balance and slag viscosity of the flux coating system, improving slag coverage; mica powder, with its flake structure, enhances the plasticity and lubricity of the wet flux coating, reducing the risk of cracking during coating, drying, and baking; kaolin improves the adhesion, suspension, and shape retention of the wet flux coating, enhancing the integrity of the coated material after coating; potassium feldspar powder participates in slag formation and provides potassium, helping to improve slag flowability, slag removal, and arc stability. The combination of these four components, without compromising the low-hydrogen alkaline flux coating system, balances coating formability, coating strength, slag coverage, slag removal, and arc stabilization, ensuring that the composite pore-forming agent improves low-temperature arc ignition performance while the electrode retains good overall welding process performance.

[0020] As a preferred technical solution of the present invention, in step S3, the specific baking process is as follows: raising the temperature from room temperature to 110-130℃ and keeping it warm for 2-3 hours; continuing to raise the temperature to 230-260℃ and keeping it warm for 1.5-2.5 hours; then raising the temperature to 350-390℃ and keeping it warm for 1.5-2.5 hours.

[0021] The stepped baking process gradually removes free and bound water from the coating, promotes the dehydration and solidification of water glass, reduces the moisture content of the coating, and minimizes the risk of cracking, blistering, or peeling due to rapid water loss. Simultaneously, this baking process helps the microcrystalline cellulose template form appropriate porosity, allowing the composite pore-forming agent to transform into pore-wall-enriched functionalized microchannels within the coating, thus achieving a balance between low-hydrogen control, coating strength, and low-temperature arc-ignition performance.

[0022] As a preferred technical solution of the present invention, the method for preparing aluminum-doped zinc oxide is as follows: zinc salt and aluminum salt are added to deionized water, stirred and dissolved to obtain a zinc-aluminum mixed salt solution; the pH of the system is adjusted to alkaline under water bath heating and stirring conditions and aged; filtered, the solid phase is collected, washed, dried and calcined to obtain the solution.

[0023] In a preferred embodiment of the present invention, the zinc salt is at least one of zinc acetate, zinc nitrate, or their hydrates, and the aluminum salt is at least one of aluminum nitrate, aluminum chloride, or their hydrates; in the zinc-aluminum mixed salt solution, Al 3 + Zn 2+ The molar ratio is 0.005-0.050: 0.950-0.995.

[0024] As a preferred technical solution of the present invention, the step of adjusting the pH of the system to alkaline and aging it under water bath heating and stirring conditions refers to adjusting the pH of the system to 8.5-10.5 with sodium hydroxide solution and aging it for 2-4 hours under water bath heating and stirring conditions at 50-70℃; in the preparation method of aluminum-doped zinc oxide, calcination is carried out at 350-550℃ for 2-4 hours in an air atmosphere.

[0025] The aluminum-doped zinc oxide was prepared by aqueous co-precipitation, aging, drying, and calcination. This method enables Zn... 2+ And Al 3+ Uniform mixing in solution and simultaneous precipitation under alkaline conditions improves the dispersion uniformity of aluminum in the zinc oxide system, avoiding localized agglomeration and uneven doping caused by mechanical mixing. By controlling the Al content... 3+ With Zn 2+ The molar ratio, precipitation pH, aging temperature and calcination temperature can be adjusted to regulate the defect structure and electric field response capability of aluminum-doped zinc oxide, making it more likely to generate micro-conduction response in the early stage of low-temperature arc ignition as a defect conductive seed phase.

[0026] Another objective of this invention is to provide a welding electrode coating that improves low-temperature arc ignition performance, which is prepared using the above-described method for preparing a welding electrode coating that improves low-temperature arc ignition performance.

[0027] The beneficial effects of this invention are: (1) The electrode coating for improving low-temperature arc ignition performance disclosed in this invention and its preparation method are prepared by pre-composite microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax, and then spray-anchored with silicate diluent to obtain a composite pore-forming agent. This composite pore-forming agent enables aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax to be pre-loaded on the surface of the microcrystalline cellulose template, forming pore wall-enriched functionalized microchannels after the electrode coating is baked, avoiding random dispersion of functional powders in the coating matrix, thereby improving the effective utilization rate of functional components in the arc ignition end orifice, orifice wall, and partial discharge micro-region, and improving the primary arc ignition and re-arc ignition performance in low-temperature environments.

[0028] (2) The electrode coating for improving low-temperature arc ignition performance disclosed in this invention and its preparation method involve spraying a silicate diluent composed of potassium silicate, sodium silicate, and deionized water onto a template premix powder, which is then dried to form a potassium-sodium composite silicate activated anchoring layer. This activated anchoring layer can, on the one hand, improve the bonding stability between the functional powder and the microcrystalline cellulose template, reducing powder shedding, agglomeration, and segregation during subsequent dry mixing, wet mixing, and pressure coating processes; on the other hand, it can provide a local potassium and sodium activation environment during arc ignition, assisting in ionization and arc stabilization, thereby shortening the average arc ignition time and reducing the electrode sticking rate.

[0029] (3) The electrode coating for improving low-temperature arc ignition performance disclosed in this invention and its preparation method utilize a coating base powder composed of marble powder, fluorite powder, rutile titanium dioxide, medium-carbon ferromanganese powder, ferrosilicon powder, a modifier, and iron powder. This coating base powder maintains the basic welding performance required for low-hydrogen basic electrodes. Marble powder and fluorite powder form the basic basic slag system, rutile titanium dioxide improves arc stability and slag coverage, medium-carbon ferromanganese powder and ferrosilicon powder achieve deoxidation and alloy transition, iron powder improves deposition efficiency and arc stability, and the modifier improves pressure coating formability, slag fluidity, and slag removal. The resulting coating base powder improves low-temperature arc ignition performance while still maintaining coating strength, low-hydrogen control, weld formation, and low-temperature impact toughness.

[0030] (4) The electrode coating for improving low-temperature arc ignition performance disclosed in this invention and its preparation method are prepared by using aqueous co-precipitation, aging, drying and calcination to prepare aluminum-doped zinc oxide, so that aluminum element is introduced into the zinc oxide system more uniformly, forming a functional powder with defect conductivity response capability. When aluminum-doped zinc oxide and barium titanate are enriched together in the hole wall region, barium titanate can enhance the local electric field near the hole opening and hole wall in the early stage of low-temperature arc ignition, and aluminum-doped zinc oxide preferentially forms a micro-conductivity response under the action of this local high electric field; at the same time, anhydrous borax forms a low-temperature liquid phase bridge in the early stage of heating, and cerium oxide plays a role in stabilizing the arc and improving metallurgy after the arc is established. Thus, a continuous synergistic mechanism of local electric field enhancement-defect conductivity response-low-temperature liquid phase bridging-high-temperature arc stabilization is formed, which improves the success rate of first arc ignition, the success rate of re-arcing, and the arc ignition stability after low-temperature storage and transportation of the electrode in low-temperature environment. Detailed Implementation

[0031] The claims of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of protection of the claims of the present invention are still within the scope of protection of the claims of the present invention.

[0032] Example 1 218.41 parts by mass of zinc acetate dihydrate and 1.88 parts by mass of aluminum nitrate nonahydrate were added to 1000 parts by mass of deionized water and stirred to dissolve, yielding a zinc-aluminum mixed salt solution. The pH of the system was adjusted to 8.5 with 1 mol / L sodium hydroxide solution under stirring in a 50°C water bath. The mixture was then aged for 4 hours with continued stirring. After filtration, the solid phase was collected and washed with deionized water until the filtrate was neutral in pH. The filtrate was then dried at 70°C for 12 hours to obtain the aluminum-zinc hydroxide precursor. The precursor was then dried at 350°C in air. After calcination for 2 hours, cooling, grinding, and sieving, aluminum-doped zinc oxide was obtained. 0.2 parts by mass of potassium silicate and 1 part by mass of sodium silicate were added to 12 parts by mass of deionized water and stirred until homogeneous to obtain a silicate dilution. 35 parts by mass of microcrystalline cellulose, 18 parts by mass of aluminum-doped zinc oxide, 8 parts by mass of cerium oxide, 6 parts by mass of barium titanate, and 6 parts by mass of anhydrous borax were mixed until homogeneous to obtain a template premix powder. The silicate dilution was added to the template premix powder by spraying while stirring, and the mixture was dried at 60℃ for 6 hours. Crushing and sieving yields a composite pore-forming agent. 34 parts by weight of marble powder, 15 parts by weight of fluorite powder, 8 parts by weight of rutile titanium dioxide, 7 parts by weight of medium-carbon ferromanganese powder, 3 parts by weight of ferrosilicon powder, 10 parts by weight of a regulator (composed of quartz powder, mica powder, kaolin, and potassium feldspar powder in a mass ratio of 3:1:1:2), 10 parts by weight of iron powder, and 2.5 parts by weight of the composite pore-forming agent are mixed evenly. Then, 24 parts by weight of a 38 wt% water glass solution with a modulus of 2.6 are added and the mixture is stirred for 30 minutes to obtain the drug. The wet flux coating is applied to the surface of the H08A low-carbon steel core electrode at a speed of 120 electrodes / min. After drying at 25°C for 24 hours, 10 mm of flux coating is ground off the arc-starting end to expose the core electrode end, and 20 mm of flux coating is ground off the clamping end. The temperature is then raised to 110°C and held for 2 hours, then raised to 230°C and held for 1.5 hours, and finally raised to 350°C and held for 1.5 hours. After cooling, a flux coating with a single-sided thickness of 0.70 mm and a flux coating weight coefficient of 35% is obtained.

[0033] Example 2 217.31 parts by weight of zinc acetate dihydrate and 3.75 parts by weight of aluminum nitrate nonahydrate were added to 1000 parts by weight of deionized water and stirred to dissolve, yielding a zinc-aluminum mixed salt solution. The pH of the system was adjusted to 9.0 with 1 mol / L sodium hydroxide solution under stirring in a 55°C water bath. The mixture was then aged for 2.5 h with stirring. After filtration, the solid phase was collected and washed with deionized water until the filtrate was neutral in pH. The filtrate was then dried at 80°C for 11 h to obtain an aluminum-zinc hydroxide precursor, which was calcined at 400°C in air. After calcining for 3.5 hours and cooling, the mixture is ground and sieved to obtain aluminum-doped zinc oxide. 0.4 parts by weight of potassium silicate and 1 part by weight of sodium silicate are added to 15 parts by weight of deionized water and stirred until homogeneous to obtain a silicate dilution. 40 parts by weight of microcrystalline cellulose, 22 parts by weight of aluminum-doped zinc oxide, 11 parts by weight of cerium oxide, 9 parts by weight of barium titanate, and 10 parts by weight of anhydrous borax are mixed until homogeneous to obtain a template premix powder. The silicate dilution is added to the template premix powder by spraying while stirring, and the mixture is dried at 70°C for 5 hours. Crushing and sieving yields a composite pore-forming agent. 35 parts by weight of marble powder, 16 parts by weight of fluorite powder, 8.5 parts by weight of rutile titanium dioxide, 8 parts by weight of medium-carbon ferromanganese powder, 3.5 parts by weight of ferrosilicon powder, 11 parts by weight of a regulator (composed of quartz powder, mica powder, kaolin, and potassium feldspar powder in a mass ratio of 4:2:2:3), 12 parts by weight of iron powder, and 3.0 parts by weight of the composite pore-forming agent are mixed evenly. Then, 25 parts by weight of a 39 wt% water glass solution with a modulus of 2.7 are added and the mixture is stirred for 35 minutes to obtain… The wet flux coating is applied to the surface of the H08A low-carbon steel core electrode at a speed of 130 electrodes / min. After drying at 30℃ for 15 hours, 11 mm of flux coating is ground off the arc-starting end to expose the core electrode end, and 22 mm of flux coating is ground off the clamping end. The temperature is then raised to 120℃ and held for 2.5 hours, then raised to 240℃ and held for 2.0 hours, and finally raised to 360℃ and held for 2.0 hours. After cooling, a flux coating with a single-sided thickness of 0.80 mm and a flux weight coefficient of 38% is obtained.

[0034] Example 3 214.02 parts by weight of zinc acetate dihydrate and 9.38 parts by weight of aluminum nitrate nonahydrate were added to 1000 parts by weight of deionized water and stirred to dissolve, yielding a zinc-aluminum mixed salt solution. The pH of the system was adjusted to 9.5 with 1 mol / L sodium hydroxide solution under stirring in a 60°C water bath. The mixture was then aged for 3 hours with continued stirring. After filtration, the solid phase was collected and washed with deionized water until the filtrate was neutral in pH. The filtrate was then dried at 85°C for 10 hours to obtain the aluminum-zinc hydroxide precursor, which was calcined at 450°C in air. After 3 hours of cooling, the mixture is ground and sieved to obtain aluminum-doped zinc oxide. 0.5 parts by weight of potassium silicate and 1 part by weight of sodium silicate are added to 18 parts by weight of deionized water and stirred until homogeneous to obtain a silicate dilution. 42 parts by weight of microcrystalline cellulose, 25 parts by weight of aluminum-doped zinc oxide, 13 parts by weight of cerium oxide, 11 parts by weight of barium titanate, and 12 parts by weight of anhydrous borax are mixed until homogeneous to obtain a template premix powder. The silicate dilution is added to the template premix powder by spraying while stirring, and the mixture is dried at 75°C for 4 hours, crushed, and... The composite pore-forming agent was obtained by sieving. 36 parts by weight of marble powder, 17 parts by weight of fluorite powder, 9 parts by weight of rutile titanium dioxide, 8.5 parts by weight of medium-carbon ferromanganese powder, 4 parts by weight of ferrosilicon powder, 13 parts by weight of regulator (composed of quartz powder, mica powder, kaolin, and potassium feldspar powder in a mass ratio of 5:2.5:2.5:4), 13 parts by weight of iron powder, and 3.5 parts by weight of the composite pore-forming agent were mixed evenly. Then, 26 parts by weight of a 41 wt% water glass solution with a modulus of 2.9 were added and stirred for 35 minutes to obtain… The wet flux coating is applied to the surface of the H08A low-carbon steel core electrode at a speed of 140 electrodes / min. After drying at 35℃ for 18 hours, 11 mm of flux coating is ground off the arc-starting end to expose the core electrode end, and 23 mm of flux coating is ground off the clamping end. The temperature is then raised to 120℃ and held for 2.5 hours, then raised to 245℃ and held for 2.0 hours, and finally raised to 370℃ and held for 2.0 hours. After cooling, a flux coating with a single-sided thickness of 0.85 mm and a flux weight coefficient of 40% is obtained.

[0035] Example 4 210.73 parts by weight of zinc acetate dihydrate and 15.01 parts by weight of aluminum nitrate nonahydrate were added to 1000 parts by weight of deionized water and stirred to dissolve, yielding a zinc-aluminum mixed salt solution. The pH of the system was adjusted to 10.0 with 1 mol / L sodium hydroxide solution under stirring in a 65°C water bath. The mixture was then aged for 2.5 h with continued stirring. After filtration, the solid phase was collected and washed with deionized water until the filtrate was neutral. The filtrate was then dried at 95°C for 8.5 h to obtain the aluminum-zinc hydroxide precursor. The precursor was then dried at 500 °C in air. Calcination at ℃ for 2.5 h, followed by cooling, grinding, and sieving to obtain aluminum-doped zinc oxide; 0.7 parts by mass of potassium silicate and 1 part by mass of sodium silicate were added to 22 parts by mass of deionized water and stirred evenly to obtain a silicate dilution solution; 48 parts by mass of microcrystalline cellulose, 30 parts by mass of aluminum-doped zinc oxide, 16 parts by mass of cerium oxide, 15 parts by mass of barium titanate, and 16 parts by mass of anhydrous borax were mixed evenly to obtain a template premix powder; the silicate dilution solution was added to the template premix powder by spraying while stirring, and dried at 85℃ for 2 hours. After 5 hours of crushing and sieving, a composite pore-forming agent was obtained. 37 parts by weight of marble powder, 18 parts by weight of fluorite powder, 9 parts by weight of rutile titanium dioxide, 9 parts by weight of medium-carbon ferromanganese powder, 4.5 parts by weight of ferrosilicon powder, 14 parts by weight of regulator (composed of quartz powder, mica powder, kaolin, and potassium feldspar powder in a mass ratio of 7:3:3:5), 15 parts by weight of iron powder, and 4.2 parts by weight of the composite pore-forming agent were mixed evenly. Then, 26 parts by weight of a 42 wt% water glass solution with a modulus of 3.1 were added and stirred for 38 minutes to obtain… The wet flux coating is applied to the surface of the H08A low-carbon steel core at a speed of 150 electrodes / min. It is then dried at 42℃ for 14 hours. After drying, 12mm of flux coating is ground off the arc-starting end to expose the core end, and 25mm of flux coating is ground off the clamping end. The temperature is then raised to 125℃ and held for 2.5 hours, then raised to 250℃ and held for 2.5 hours, and finally raised to 380℃ and held for 2.5 hours. After cooling, a welding electrode flux coating with a single-sided thickness of 0.90mm and a flux weight coefficient of 44% is obtained.

[0036] Example 5 208.53 parts by mass of zinc acetate dihydrate and 18.76 parts by mass of aluminum nitrate nonahydrate were added to 1000 parts by mass of deionized water and stirred to dissolve, yielding a zinc-aluminum mixed salt solution. The pH of the system was adjusted to 10.5 using a 1 mol / L sodium hydroxide solution under stirring in a 70°C water bath. The mixture was then aged for 2 hours with continued stirring. After filtration, the solid phase was collected and washed with deionized water until the filtrate reached a neutral pH. The filtrate was then dried at 100°C for 8 hours to obtain the aluminum-zinc hydroxide precursor. The precursor was then cured at 550°C in air. Calcination for 2 hours, followed by cooling, grinding, and sieving to obtain aluminum-doped zinc oxide; 0.8 parts by weight of potassium silicate and 1 part by weight of sodium silicate were added to 24 parts by weight of deionized water and stirred evenly to obtain a silicate dilution; 35-50 parts by weight of microcrystalline cellulose, 32 parts by weight of aluminum-doped zinc oxide, 18 parts by weight of cerium oxide, 16 parts by weight of barium titanate, and 18 parts by weight of anhydrous borax were mixed evenly to obtain a template premix powder; the silicate dilution was added to the template premix powder by spraying while stirring, and dried at 90℃ for 2 hours. h. Crushing and sieving yields a composite pore-forming agent; 38 parts by weight of marble powder, 19 parts by weight of fluorite powder, 10 parts by weight of rutile titanium dioxide, 10 parts by weight of medium-carbon ferromanganese powder, 5 parts by weight of ferrosilicon powder, 15 parts by weight of regulator (composed of quartz powder, mica powder, kaolin and potassium feldspar powder in a mass ratio of 8:4:4:6), 16 parts by weight of iron powder and 4.5 parts by weight of composite pore-forming agent are mixed evenly, and 28 parts by weight of water glass solution with a modulus of 3.2 and 43 wt% are added and stirred for 40 min. The wet flux coating was obtained and pressed onto the surface of the H08A low carbon steel core at a speed of 160 electrodes / min. It was then dried at 45℃ for 12 hours. After drying, 12 mm of flux coating was ground off the arc-starting end to expose the core end, and 25 mm of flux coating was ground off the clamping end. The room temperature was raised to 130℃ and held for 3 hours, then raised to 260℃ and held for 2.5 hours, and then raised to 390℃ and held for 2.5 hours. After cooling, a welding electrode flux coating with a single-sided thickness of 0.95 mm and a flux weight coefficient of 45% was obtained.

[0037] Comparative Example 1 The difference from Example 3 is that no composite pore-forming agent is added, and the reduced amount is made up with an equal mass of iron powder, while the rest of the operations and steps remain unchanged.

[0038] Comparative Example 2 The difference from Example 3 is that microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax are directly mixed with the drug coating base powder to obtain the drug coating dry powder, while the remaining operations and steps remain unchanged.

[0039] Comparative Example 3 The difference from Example 3 is that barium titanate is not added, and its reduced amount is made up with an equal mass of microcrystalline cellulose, while the rest of the operations and steps remain unchanged.

[0040] Comparative Example 4 The difference from Example 3 is that aluminum-doped zinc oxide is not added, and the reduction is made up with an equal mass of microcrystalline cellulose, while the rest of the operations and steps remain unchanged.

[0041] Comparative Example 5 The difference from Example 3 is that 12 parts by weight of anhydrous borax are first added to 48 parts by weight of deionized water to prepare a borate aqueous dispersion, and then mixed with silicate dilution solution and template premix powder through spray drying. The remaining operations and steps remain unchanged.

[0042] Comparative Example 6 The difference from Example 3 is that aluminum-doped zinc oxide is replaced with an equal mass of nano zinc oxide, while the rest of the operations and steps remain unchanged.

[0043] Performance testing The electrode coatings prepared in Examples 1-5 and Comparative Examples 1-6 were placed in a low-temperature chamber at -30℃±2℃ for 4 hours and then tested within 60 seconds after being removed.

[0044] DC reverse polarity was used, with a welding current of 160A. The test plate was a Q355 steel plate, 12mm thick, with a surface that had been ground and rust-removed. Each group of welding electrodes was tested for 200 arc initiation attempts, and the success rate of arc initiation on the first attempt, the average arc initiation time, and the electrode adhesion rate were recorded. A successful arc initiation was defined as the formation of a continuous and stable arc within 2 seconds after the electrode tip contacted the test plate, and the arc continuing to burn for no less than 3 seconds.

[0045] Re-arc re-ignition test: After each welding rod burns for 60mm, the arc is manually interrupted. After cooling for 30s, the arc is re-ignited on the original test plate. Each group is tested 100 times, and the success rate of re-arc re-ignition is recorded.

[0046] Arc ignition test after low temperature storage and transportation: Place the welding rod at -40℃±2℃ for 24 hours, and then restore it to -30℃±2℃ to test the arc ignition success rate.

[0047] The diffusible hydrogen content was tested in accordance with GB / T 3965-2020.

[0048] The impact absorption energy at -40℃ was tested according to GB / T 5117-2012.

[0049] The test results are shown in Table 1 below: Table 1

[0050] As shown in Table 1, Examples 1-5 had a high success rate of arc ignition at -30℃, and the average arc ignition time was significantly shortened and the sticking rate was significantly reduced.

[0051] Comparative Example 1, without the addition of the composite pore-forming agent, exhibited a lower first-attempt arc-ignition success rate at -30°C, a longer average arc-ignition time, an increased sticking rate, and a significant decrease in both re-arcing success rate and arc-ignition success rate after low-temperature storage. Comparative Example 2, without prior preparation of the composite pore-forming agent, directly dry-mixed the functional components with the drug coating base powder; its first-attempt arc-ignition success rate was lower than that of Example 3, and the average arc-ignition time and sticking rate were also significantly deteriorated. Comparative Example 3, without the addition of barium titanate, exhibited a lower first-attempt arc-ignition success rate than Example 3, while both the average arc-ignition time and sticking rate increased. Comparative Example 4, without the addition of aluminum-doped zinc oxide, showed a decreased first-attempt arc-ignition success rate, a longer average arc-ignition time, and an increased sticking rate. Comparative Example 5, by first adding anhydrous borax to water to prepare a borate aqueous dispersion, and then spraying it together with a silicate dilution solution, resulted in a lower first-attempt arc-ignition success rate, an increased diffuse hydrogen content, and a decreased impact absorption energy at -40°C. Comparative Example 6, by replacing aluminum-doped zinc oxide with an equal mass of ordinary nano-zinc oxide, showed a lower first-attempt arc-ignition success rate than that of Example 3.

[0052] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, features in the embodiments of the present invention can be combined with each other unless otherwise specified.

Claims

1. A method for preparing a welding electrode coating that improves low-temperature arc ignition performance, characterized in that, Includes the following steps: S1. Microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax are mixed evenly to obtain a template premix powder. Silicate diluent is added to the template premix powder by spraying while stirring. The mixture is then dried, crushed, and sieved to obtain a composite pore-forming agent. The mass ratio of microcrystalline cellulose, aluminum-doped zinc oxide, cerium oxide, barium titanate, and anhydrous borax is 35-50:18-32:8-18:6-16:6-18. S2. The composite pore-forming agent is mixed evenly with the drug coating base powder to obtain dry drug coating powder, and water glass solution is added and stirred evenly to obtain wet drug coating material; the drug coating base powder is composed of marble powder, fluorite powder, rutile titanium dioxide, medium carbon manganese iron powder, ferrosilicon powder, regulator and iron powder. S3. The wet flux is pressed onto the surface of the welding core, and after drying, grinding and baking, the flux of the welding electrode is obtained.

2. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 1, characterized in that, In step S1, the silicate diluent is composed of potassium silicate, sodium silicate and deionized water in a mass ratio of 0.2-0.8:1:12-24.

3. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 1, characterized in that, In step S2, the mass ratio of the composite pore-forming agent, the coating base powder, and the water glass solution is 2.5-4.5:95.5-97.5:24-28; the coating base powder is composed of marble powder, fluorite powder, rutile titanium dioxide, medium carbon manganese iron powder, ferrosilicon powder, regulator, and iron powder in a mass ratio of 34-38:15-19:8-10:7-10:3-5:10-15:10-16.

4. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 3, characterized in that, The regulator includes one or more of quartz powder, mica powder, kaolin, and potassium feldspar powder.

5. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 4, characterized in that, The regulator is composed of quartz powder, mica powder, kaolin and potassium feldspar powder in a mass ratio of 3-8:1-4:1-4:2-6.

6. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 1, characterized in that, In step S3, the specific baking process is as follows: raise the temperature from room temperature to 110-130℃ and keep it warm for 2-3 hours; continue to raise the temperature to 230-260℃ and keep it warm for 1.5-2.5 hours; then raise the temperature to 350-390℃ and keep it warm for 1.5-2.5 hours.

7. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 1, characterized in that, The method for preparing aluminum-doped zinc oxide is as follows: zinc salt and aluminum salt are added to deionized water, stirred and dissolved to obtain a zinc-aluminum mixed salt solution; The system was adjusted to alkaline pH under water bath heating and stirring conditions and aged, then filtered, and the solid phase was collected, washed, dried, and calcined to obtain the final product.

8. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 7, characterized in that, The zinc salt is at least one of zinc acetate, zinc nitrate, or their hydrates, and the aluminum salt is at least one of aluminum nitrate, aluminum chloride, or their hydrates; in the zinc-aluminum mixed salt solution, the molar ratio of Al3+ to Zn2+ is 0.005-0.050:0.950-0.

995.

9. The method for preparing a welding electrode coating with improved low-temperature arc ignition performance according to claim 7, characterized in that, The process of adjusting the pH of the system to alkaline and aging it under water bath heating and stirring conditions refers to adjusting the pH of the system to 8.5-10.5 using sodium hydroxide solution and aging it for 2-4 hours under water bath heating and stirring conditions at 50-70℃; in the preparation method of aluminum-doped zinc oxide, calcination is carried out at 350-550℃ for 2-4 hours in an air atmosphere.

10. A welding electrode coating for improving low-temperature arc ignition performance, characterized in that, It is prepared using the method for preparing a welding electrode coating that improves low-temperature arc ignition performance according to any one of claims 1-9.

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