A special coating for manganese steel frog V method casting and a preparation method thereof

Abstract

The present application relates to a kind of manganese steel crossing V method casting special paint and its preparation method, it is composed of following components: composite refractory aggregate, composite binder, composite suspending agent, thixotropic aid, sintering aid, wetting aid, solvent.The present application carries out new matching and compound design to each core component, solve the technical problems that the existing V method casting paint is poor in adhesion on the surface of plastic film, easy to flow and accumulate, large in gas evolution, difficult to shell peeling, simultaneously reduce the gas evolution of paint, form continuous and uniform coating after paint spraying, easy to sinter at high temperature and high shell peeling rate, effectively avoid the defects such as pore, sand sticking, sand flushing of manganese steel crossing casting, the surface finish of casting is improved, and subsequent cleaning difficulty is greatly reduced.The preparation method of the present application is simple, easy to industrial production, and the comprehensive performance of paint is excellent, suitable for the severe requirements of manganese steel crossing V method casting, and practical.

Description

Technical Field

[0001] This invention relates to the field of casting coating technology, and in particular to a coating specifically for V-process casting of manganese steel forks and its preparation method. Background Technology

[0002] Foundry coating is a core auxiliary material for sand casting. It is applied to the surface of sand molds and cores. Its core function is to achieve physical and chemical isolation between liquid metal and sand molds / cores. It can prevent liquid metal from penetrating the gaps between sand particles and causing mechanical sand adhesion, and inhibit the chemical reaction between the molten metal and the surface of the mold / core to avoid chemical sand adhesion. At the same time, it can effectively reduce casting defects such as sand inclusions, sand flushing, and slag holes, and directly determine the surface quality and internal properties of castings.

[0003] V-process casting, as an advanced vacuum-sealed molding technology, has become the mainstream casting process for large railway castings such as manganese steel frogs due to its advantages such as high dimensional accuracy, low surface roughness, high sand recycling rate, and clean production environment. However, the process characteristics of V-process casting place much stricter requirements on casting coatings than traditional sand casting: the coating must be applied directly to the surface of a plastic film and can only be applied by spraying. The coating's adhesion, thixotropy, anti-flow properties, and high-temperature sintering properties directly determine the integrity of the coating, thus affecting the yield and quality of the castings.

[0004] Currently available casting coatings are primarily designed for traditional sand mold surface application. However, when applied to the plastic film surface of manganese steel turnout V-process casting, several technical drawbacks arise: First, the interfacial affinity between the coating and the plastic film is poor, resulting in insufficient adhesion. This is especially problematic when spraying on vertical surfaces of the plastic film, easily leading to coating runs and breaks, preventing the formation of a continuous and uniform coating and causing serious defects such as sand inclusions, sand trapping, and sand adhesion in the casting. Second, the coating's thixotropic and anti-flow properties are inadequate; even if a continuous coating can be formed, it is prone to defects on vertical surfaces. The coating is uneven in thickness due to flow and accumulation, which can easily lead to defects such as porosity and slag porosity in the casting after pouring. Third, existing coatings for manganese steel turnout castings mostly use magnesia powder as the single refractory aggregate. Magnesia powder is difficult to sinter at high temperatures, and the sintering aids are of a single type with poor synergy. During the sand removal and cleaning of the casting, the coating layer cannot be effectively shelled and peeled off, and it adheres to the surface of the casting, which greatly increases the labor and time costs of subsequent cleaning. Fourth, the coating has poor dispersibility and the components are prone to agglomeration, resulting in low coating density. During high-temperature pouring, local gas generation is prone to occur, which further aggravates the porosity defects in the casting.

[0005] To address the aforementioned issues, existing technologies have implemented simple component blending for V-process casting coatings, but these improvements are mostly focused on individual properties and have not achieved a synergistic enhancement of the coating's overall performance. Furthermore, existing coatings have not introduced commercially available new functional components, resulting in insufficient optimization of the coating's interfacial bonding, dispersion stability, and high-temperature sintering synergy. Consequently, the core performance of these coatings still cannot meet the high-quality requirements of V-process casting of manganese steel turnouts.

[0006] Therefore, developing a special coating for V-process casting of manganese steel turnouts that combines high adhesion, excellent anti-flow properties, low gas generation, easy sintering at high temperatures, and high peeling rate has become a technical problem that urgently needs to be solved in the current casting industry. Summary of the Invention

[0007] In view of this, the purpose of this invention is to overcome the shortcomings of the prior art and provide a coating specifically for V-process casting of manganese steel frogs and its preparation method. Through a novel compound design and ratio optimization of each component, the coating's adhesion, anti-flow properties, dispersion stability, high-temperature sintering properties, and low gas generation are synergistically improved. This solves the technical defects of existing coatings, effectively improves the surface quality of manganese steel frog castings, reduces the difficulty of subsequent cleaning, and ensures that the coating preparation process is simple and easy to industrialize.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 61-67% composite refractory aggregate, 1.6-2.1% composite binder, 2.2-3.0% composite suspending agent, 1.3-1.9% thixotropic agent, 2.1-2.9% sintering aid, 0.4-0.7% wetting and dispersing aid, 0.2-0.5% functional modifying agent, and 21-29% composite solvent; wherein the composite refractory aggregate is composed of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano talc powder in a mass ratio of (44-49):(21-26):(9-14):(7-11):(4-6); wherein the composite binder is composed of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and organosilicon-modified epoxy resin in a mass ratio of (49-54):(26-31):(11-16):(6-9).

[0009] Preferably, the magnesia powder is fused magnesia powder with an average particle size of 3000-5000 mesh; the mullite powder has an average particle size of 1000-1500 mesh; the andalusite powder has an average particle size of 1200-1800 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; and the nano-talc powder has a particle size of 20-100 nm.

[0010] Preferably, the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

[0011] Preferably, the composite suspending agent is composed of lithium-based bentonite, organic bentonite, attapulgite, and sepiolite powder in a mass ratio of (39-44):(26-31):(19-24):(6-9).

[0012] Preferably, the average particle size of the composite suspending agent is 400-800 mesh; the organic bentonite is BENTONE® 34 organic bentonite.

[0013] Preferably, the thixotropic agent is a compound of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of (34-39):(26-31):(21-26):(6-11).

[0014] Preferably, the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the diatomaceous earth has an average particle size of 400-800 mesh; and the magnesium aluminum silicate has an average particle size of 500-1000 mesh.

[0015] Preferably, the sintering aid is composed of silicon micro powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of (58-63):(24-29):(7-12):(3-6).

[0016] Preferably, the average particle size of the sintering aid is 800-1200 mesh.

[0017] Preferably, the wetting and dispersing aid is compounded from polyethylene glycol 600, sodium dodecylbenzene sulfonate, and polycarboxylate dispersant in a mass ratio of (1-2):1:(0.5-1).

[0018] Preferably, the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant.

[0019] Preferably, the functional modifying agent is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of (2-3):1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; and the nano titanium dioxide has a particle size of 20 nm.

[0020] Preferably, the composite solvent is a mixture of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of (7-8):1:(0.5-1).

[0021] Another object of the present invention is to provide a method for preparing a coating specifically for V-process casting of manganese steel forks, comprising the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them and put them into a ball mill. Ball mill at a speed of 220-320 r / min for 2-3 hours, and pass them through a 200-325 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the formula, and add them to 1 / 2-3 / 4 of the mass of the composite solvent. Mix and dissolve the mixture for 16-22 minutes under stirring conditions of 52-62℃ and 320-420r / min. During this period, add the functional modifier in 2-3 portions, and simultaneously use ultrasonic dispersion at 200-300W for 5-8 minutes to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a speed of 5-8 kg / min, while stirring at a high speed of 850-1050 r / min for 32-42 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1-2 hours until the coating particle size D90 ≤ 45μm. Then filter it through a 300-400 mesh sieve to obtain the coating specifically for V-process casting of manganese steel forks.

[0022] The beneficial effects of adopting the above technical solution are as follows: 1. This invention, through a multi-component synergistic compounding design of composite refractory aggregates, overcomes the limitations of existing technologies using only magnesia powder aggregates, achieving an unexpected improvement in the high-temperature performance of coatings. Compared to the problems of existing single magnesia powder coatings being difficult to sinter at high temperatures and prone to detachment, this invention uses five components, including magnesia powder, mullite powder, and andalusite powder, compounded in a specific ratio. Utilizing the complementary high-temperature properties of each aggregate, it not only significantly improves the high-temperature refractoriness and sintering density of the coating, but also unexpectedly solves the problem of concentrated local gas generation during high-temperature casting, reducing the amount of gas generated in the coating and effectively avoiding defects such as porosity and slag inclusions in castings. Simultaneously, it greatly enhances the interfacial affinity between the coating and the plastic film, enabling the formation of a continuous and uniform coating even in vertical spraying scenarios, completely solving the technical pain points of existing coatings being prone to dripping and breaking during vertical spraying.

[0023] 2. The innovative combination of composite binders and functional modifying agents achieves a synergistic breakthrough in coating adhesion and stability, producing an interface bonding effect that exceeds expectations. Addressing the core challenge of poor adhesion between coatings and V-process cast plastic films in existing technologies, this invention precisely blends four binders—phenolic resin, rosin-modified phenolic resin, etc.—combined with functional modifying agents composed of organically modified montmorillonite and nano-titanium dioxide. This not only improves the adhesion between the coating and the plastic film but also unexpectedly enhances the dispersion stability of the coating, effectively suppressing component agglomeration and significantly increasing coating density. Simultaneously, it considers the coating's spray application properties, avoiding problems such as spray gun clogging and uneven coating thickness. Compared to existing coatings adapted for traditional sand molds, its specificity for V-process cast plastic films is greatly improved, broadening the coating's applicable scenarios.

[0024] 3. The scientific formulation of thixotropic additives and suspending agents unexpectedly achieves a dual optimization of coating anti-flow properties and storage stability, resolving the technical contradiction that existing technologies struggle to achieve simultaneously. Existing coatings either lack sufficient thixotropy, leading to flow on vertical surfaces, or exhibit excessive thixotropy, affecting spraying smoothness. This invention, through the synergistic effect of four thixotropic additives (polyvinyl butyral, diatomaceous earth, etc.) and a composite suspending agent, not only gives the coating excellent anti-flow properties, preventing flow and accumulation after vertical spraying, and controlling coating thickness deviation within ±0.1mm, but also unexpectedly improves the coating's storage stability. It exhibits no sedimentation or stratification after more than 6 months of storage at room temperature and can be used directly without secondary stirring, significantly reducing operational difficulty and material waste in the production process. Compared to the short shelf life and easy sedimentation of existing coatings, its practicality is significantly improved.

[0025] 4. The multi-component compound design of sintering aids achieves synergistic optimization of high-temperature sintering of the coating and subsequent delamination, resulting in unexpected improvements in production efficiency and cost savings. Existing coatings, due to their single sintering aid and poor synergy, are difficult to delaminate during casting removal, requiring extensive manual cleaning, which is time-consuming and labor-intensive. This invention uses four sintering aids, including silica powder and iron oxide red powder, compounded in a specific ratio. This not only promotes rapid sintering of the coating at high temperatures to form a dense protective shell, effectively preventing molten metal penetration and chemical reactions, but also unexpectedly enables the coating to automatically embrittle and detach after the casting cools, achieving a delamination rate of over 95%. This significantly reduces the labor and time costs of subsequent cleaning, improving cleaning efficiency by over 60% compared to existing technologies, significantly reducing the production cost of manganese steel turnouts, and improving casting production efficiency.

[0026] 5. The synergistic optimization of the overall components of this invention exceeds expectations, achieving a comprehensive leap in the overall performance of the coating and breaking through the limitations of existing technologies that only improve a single performance. Compared to existing technologies that can only specifically optimize a certain performance and cannot meet comprehensive needs, this invention, through the precise proportioning and synergistic design of each component, enables the coating to simultaneously possess multiple advantages such as high adhesion, excellent anti-flow properties, low gas evolution, easy high-temperature sintering, good descrambling properties, and stable storage. It not only effectively solves various technical defects of existing coatings when applied to the V-process casting of manganese steel forks, but also unexpectedly improves the surface quality of manganese steel fork castings, reducing surface roughness and increasing casting yield, fully meeting the high-quality requirements of manganese steel fork V-process casting. At the same time, the preparation process is simple and easy to industrialize, possessing extremely strong industrial application value. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1

[0028] A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 61% composite refractory aggregate, 1.6% composite binder, 2.2% composite suspending agent, 1.3% thixotropic agent, 2.1% sintering aid, 0.4% wetting and dispersing aid, 0.2% functional modifying agent, and 21% composite solvent. The composite refractory aggregate is a mixture of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano-talc powder in a mass ratio of 44:21:9:7:4. The composite binder is a mixture of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and silicone-modified epoxy resin in a mass ratio of 49:26:11:6.

[0029] The magnesia powder is fused magnesia powder with an average particle size of 3000 mesh; the mullite powder has an average particle size of 1000 mesh; the andalusite powder has an average particle size of 1200 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; the nano talc powder has a particle size of 20 nm; the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

[0030] The composite suspending agent is composed of lithium-based bentonite, organo-bentonite, attapulgite, and sepiolite powder in a mass ratio of 39:26:19:6; the average particle size of the composite suspending agent is 400 mesh; the organo-bentonite is BENTONE® 34 organo-bentonite; the thixotropic agent is composed of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of 34:26:21:6; the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the average particle size of the diatomaceous earth is 400 mesh; and the average particle size of the magnesium aluminum silicate is 500 mesh.

[0031] The sintering aid is composed of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of 58:24:7:3; the average particle size of the sintering aid is 800 mesh; the wetting and dispersing aid is composed of polyethylene glycol 600, sodium dodecylbenzene sulfonate, and polycarboxylate dispersant in a mass ratio of 1:1:0.5; the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant; the functional modification aid is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of 2:1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the particle size of the nano titanium dioxide is 20 nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of 7:1:0.5.

[0032] A method for preparing a coating specifically for V-process casting of manganese steel fork pigeons includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them and put them into a ball mill. Ball mill at 220 r / min for 2 hours, and pass them through a 200 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the ratio, add them to 1 / 2 of the composite solvent, and mix and dissolve them at 52℃ and 320r / min for 16min. During this period, add the functional modifier in two batches and simultaneously use 200W ultrasonic dispersion for 5min to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a speed of 5 kg / min, while stirring at a high speed of 1050 r / min for 42 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1 hour until the coating particle size D90 ≤ 45 μm. Then filter it through a 300-mesh sieve to obtain the coating specifically for the V-process casting of manganese steel forks. Example 2

[0033] A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 63% composite refractory aggregate, 1.8% composite binder, 2.4% composite suspending agent, 1.5% thixotropic agent, 2.3% sintering aid, 0.5% wetting and dispersing aid, 0.3% functional modifying agent, and 23% composite solvent. The composite refractory aggregate is a mixture of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano-talc powder in a mass ratio of 45:23:11:8:4.5. The composite binder is a mixture of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and silicone-modified epoxy resin in a mass ratio of 51:27:13:7.

[0034] The magnesia powder is fused magnesia powder with an average particle size of 3500 mesh; the mullite powder has an average particle size of 1200 mesh; the andalusite powder has an average particle size of 1300 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; the nano talc powder has a particle size of 40 nm; the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

[0035] The composite suspending agent is composed of lithium-based bentonite, organo-bentonite, attapulgite, and sepiolite powder in a mass ratio of 41:28:21:7; the average particle size of the composite suspending agent is 500 mesh; the organo-bentonite is BENTONE® 34 organo-bentonite; the thixotropic agent is composed of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of 35:28:23:7; the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the average particle size of the diatomaceous earth is 500 mesh; and the average particle size of the magnesium aluminum silicate is 600 mesh.

[0036] The sintering aid is composed of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of 60:25:8:4; the average particle size of the sintering aid is 900 mesh; the wetting and dispersing aid is composed of polyethylene glycol 600, sodium dodecylbenzene sulfonate, and polycarboxylate dispersant in a mass ratio of 1.3:1:0.6; the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant; the functional modification aid is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of 2.2:1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the particle size of the nano titanium dioxide is 20 nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of 7.3:1:0.6.

[0037] A method for preparing a coating specifically for V-process casting of manganese steel fork pigeons includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them, put them into a ball mill, and ball mill them at a speed of 240 r / min for 2.3 h. Then pass them through a 250 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the ratio, add them to 1 / 2 mass of the composite solvent, mix and dissolve them at 55℃ and 350r / min for 18min, add the functional modifier in 3 portions during the process, and simultaneously use 230W ultrasonic dispersion for 6min to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a rate of 6 kg / min, while stirring at a high speed of 900 r / min for 35 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1.2 hours until the coating particle size D90 ≤ 45 μm. Then filter it through a 330 mesh sieve to obtain the coating specifically for V-process casting of manganese steel forks. Example 3

[0038] A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 64% composite refractory aggregate, 1.9% composite binder, 2.6% composite suspending agent, 1.6% thixotropic agent, 2.5% sintering aid, 0.55% wetting and dispersing aid, 0.35% functional modifying agent, and 26% composite solvent. The composite refractory aggregate is a mixture of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano-talc powder in a mass ratio of 46:24:12:9:5. The composite binder is a mixture of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and silicone-modified epoxy resin in a mass ratio of 52:29:14:7.5.

[0039] The magnesia powder is fused magnesia powder with an average particle size of 4000 mesh; the mullite powder has an average particle size of 1300 mesh; the andalusite powder has an average particle size of 1500 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; the nano talc powder has a particle size of 60 nm; the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

[0040] The composite suspending agent is composed of lithium-based bentonite, organo-bentonite, attapulgite, and sepiolite powder in a mass ratio of 42:29:22:7.5; the average particle size of the composite suspending agent is 600 mesh; the organo-bentonite is BENTONE® 34 organo-bentonite; the thixotropic agent is composed of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of 36:29:24:9; the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the average particle size of the diatomaceous earth is 600 mesh; the average particle size of the magnesium aluminum silicate is 800 mesh; the sintering aid is composed of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of 61:26:10:4.5; the average particle size of the sintering aid is 1000 mesh.

[0041] The wetting and dispersing aid is composed of polyethylene glycol 600, sodium dodecylbenzenesulfonate, and polycarboxylate dispersant in a mass ratio of 1.5:1:0.8; the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant; the functional modification aid is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of 2.5:1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the nano titanium dioxide has a particle size of 20 nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of 7.5:1:0.8.

[0042] A method for preparing a coating specifically for V-process casting of manganese steel fork pigeons includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them, put them into a ball mill, and ball mill them at a speed of 280 r / min for 2.5 h. Then pass them through a 280 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the ratio, and add them to 3 / 4 of the composite solvent by mass. Mix and dissolve for 19 minutes under stirring conditions of 58℃ and 380r / min. During this period, add the functional modifier in 3 portions and simultaneously use 250W ultrasonic dispersion for 6.5 minutes to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a rate of 6.5 kg / min, while stirring at a high speed of 950 r / min for 36 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1.5 hours until the coating particle size D90 ≤ 45 μm. Then filter it through a 350-mesh sieve to obtain the coating specifically for the V-process casting of manganese steel forks. Example 4

[0043] A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 66% composite refractory aggregate, 2% composite binder, 2.8% composite suspending agent, 1.8% thixotropic agent, 2.8% sintering aid, 0.65% wetting and dispersing aid, 0.45% functional modifying agent, and 28% composite solvent. The composite refractory aggregate is a mixture of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano-talc powder in a mass ratio of 48:25:13:10:5.5. The composite binder is a mixture of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and silicone-modified epoxy resin in a mass ratio of 53:30:15:8.5.

[0044] The magnesia powder is fused magnesia powder with an average particle size of 4500 mesh; the mullite powder has an average particle size of 1400 mesh; the andalusite powder has an average particle size of 1700 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; the nano talc powder has a particle size of 90 nm; the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; the organosilicon-modified epoxy resin is HY-1540; the composite suspending agent is composed of lithium-based bentonite, organo-bentonite, attapulgite, and sepiolite powder in a mass ratio of 43:30:23:8.5; the composite suspending agent has an average particle size of 750 mesh; the organo-bentonite is BENTONE®34 organo-bentonite.

[0045] The thixotropic agent is a compound of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of 38:30:25:10; the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the diatomaceous earth has an average particle size of 750 mesh; the magnesium aluminum silicate has an average particle size of 900 mesh; the sintering aid is a compound of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of 62:28:11:5.5; the sintering aid has an average particle size of 1100 mesh; the wetting and dispersing aid is a compound of polyethylene glycol 600, sodium dodecylbenzenesulfonate, and polycarboxylate dispersant in a mass ratio of 1.8:1:0.9; the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant.

[0046] The functional modifying agent is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of 2.8:1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the nano titanium dioxide has a particle size of 20nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of 7.8:1:0.9.

[0047] A method for preparing a coating specifically for V-process casting of manganese steel fork pigeons includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them, put them into a ball mill, and ball mill them at a speed of 310 r / min for 2.8 h. Then pass them through a 300 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the ratio, and add them to 3 / 4 of the composite solvent by mass. Mix and dissolve for 20 minutes under stirring conditions of 60℃ and 410r / min. During this period, add the functional modifier in 3 portions and simultaneously use 280W ultrasonic dispersion for 7.5 minutes to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a rate of 7.5 kg / min, while stirring at a high speed of 1000 r / min for 40 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1.8 hours until the coating particle size D90 ≤ 45 μm. Then filter it through a 390-mesh sieve to obtain the coating specifically for the V-process casting of manganese steel forks. Example 5

[0048] A coating specifically for V-process casting of manganese steel turnouts comprises the following components by mass fraction: 67% composite refractory aggregate, 2.1% composite binder, 3.0% composite suspending agent, 1.9% thixotropic agent, 2.9% sintering aid, 0.7% wetting and dispersing aid, 0.5% functional modifying agent, and 29% composite solvent. The composite refractory aggregate is a mixture of magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano-talc powder in a mass ratio of 49:26:14:11:6. The composite binder is a mixture of phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and silicone-modified epoxy resin in a mass ratio of 54:31:16:9.

[0049] The magnesia powder is fused magnesia powder with an average particle size of 5000 mesh; the mullite powder has an average particle size of 1500 mesh; the andalusite powder has an average particle size of 1800 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; the nano talc powder has a particle size of 100 nm; the phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

[0050] The composite suspending agent is composed of lithium-based bentonite, organo-bentonite, attapulgite, and sepiolite powder in a mass ratio of 44:31:24:9; the average particle size of the composite suspending agent is 800 mesh; the organo-bentonite is BENTONE® 34 organo-bentonite; the thixotropic agent is composed of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of 39:31:26:11; the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the average particle size of the diatomaceous earth is 800 mesh; the average particle size of the magnesium aluminum silicate is 1000 mesh; the sintering aid is composed of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of 63:29:12:6; the average particle size of the sintering aid is 1200 mesh.

[0051] The wetting and dispersing aid is composed of polyethylene glycol 600, sodium dodecylbenzene sulfonate, and polycarboxylate dispersant in a mass ratio of 2:1:1; the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant; the functional modification aid is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of 3:1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the nano titanium dioxide has a particle size of 20 nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of 8:1:1.

[0052] A method for preparing a coating specifically for V-process casting of manganese steel fork pigeons includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them and put them into a ball mill. Ball mill at 320 r / min for 3 hours, and pass through a 325 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the ratio, and add them to 3 / 4 of the composite solvent. Mix and dissolve them under stirring conditions of 62℃ and 420r / min for 22min. During this period, add the functional modifier in 3 portions and simultaneously use 300W ultrasonic dispersion for 8min to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a speed of 8 kg / min, while stirring at a high speed of 1050 r / min for 42 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1-2 hours until the coating particle size D90 ≤ 45 μm. Then filter it through a 400-mesh sieve to obtain the coating specifically for the V-process casting of manganese steel forks.

[0053] Comparative Example 1 A coating specifically for V-process casting of manganese steel turnouts and its preparation method are basically the same as those in Example 5, except that no functional modifying agents are added.

[0054] Comparative Example 2 A coating specifically for V-process casting of manganese steel turnouts and its preparation method are basically the same as those in Example 5, except that no wetting and dispersing aids are added.

[0055] Comparative Example 3 A coating specifically for V-process casting of manganese steel forks and its preparation method are basically the same as those in Example 5, except that an equal amount of magnesium oxide powder is used instead of nano talc powder.

[0056] Comparative Example 4 A coating specifically for V-process casting of manganese steel turnouts and its preparation method are basically the same as those in Example 5, except that an equal amount of phenolic resin is used instead of silicone-modified epoxy resin.

[0057] The following experimental methods were used to test the relevant performance of each coating example. The test results are shown in Table 1: (1) Adhesion: Refer to GB / T 9286-2021 "Cross-cut test of paint and varnish film", cross-cut spacing 1mm, 3M tape adhesion peeling, grade 0 is the best, grade 5 is the worst; (2) Anti-flow property: Refer to JB / T 9226-2008 "Coatings for Sand Casting", spray on a 60° inclined PE-20 plastic film test plate with a thickness of 0.4 mm, record the flow distance after drying for 2 hours, and no flow is 0 mm; (3) Gas Emission: Refer to JB / T 9226-2008 "Coatings for Sand Casting", gas emission meter, 850℃, sample amount 5g, record the total gas emission (mL / g). (4) Shell peeling rate: After casting and sand removal, the percentage (%) of the area of ​​shell peeling of the coating layer to the total coating area is calculated. (5) Surface roughness of castings: Ra (μm) was measured with a surface roughness tester in accordance with GB / T 1031-2009 "Surface roughness parameters and their values ​​by surface structure profile method". (6) Casting defect rate: Visual inspection and non-destructive testing were performed on the cast manganese steel frog castings after casting, and the incidence rate (%) of defects such as porosity, sand adhesion, sand flushing, and slag holes was calculated.

[0058] Table 1. Performance test results of coatings specifically for V-process casting of manganese steel frogs. project Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Adhesion (Grade) 0 2 3 1 2 Anti-flow properties (mm) 0 3 8 2 4 Gas generation (mL / g, 850℃) 4.4 23.7 26.1 21.5 24.8 Shell peeling rate (%) 99.3 91.3 84.7 93.5 89.3 Surface roughness Ra (μm) 3.2 5.8 7.3 4.1 6.2 Incidence of casting defects (%) 0 4.7 7.6 3.3 5.9 As shown in Table 1, the coating for V-process casting of manganese steel turnouts in Example 5 has the best overall performance. Its adhesion reaches grade 0, its anti-flow is 0 mm, its gas emission at 850℃ is only 4.4 mL / g, its shell peeling rate is as high as 99.3%, its surface roughness Ra of the casting is 3.2 μm, and its casting defect incidence rate is 0. In contrast, the comparative examples are all deteriorated to varying degrees because they lack functional modifiers and wetting and dispersing agents, or replace composite refractory aggregates and composite binder components.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A coating specifically for V-process casting of manganese steel forklifts, characterized in that, It is composed of the following components by mass fraction: 61-67% composite refractory aggregate, 1.6-2.1% composite binder, 2.2-3.0% composite suspending agent, 1.3-1.9% thixotropic agent, 2.1-2.9% sintering aid, 0.4-0.7% wetting and dispersing aid, 0.2-0.5% functional modifying agent, and 21-29% composite solvent; the composite refractory aggregate is compounded from magnesia powder, mullite powder, andalusite powder, acid-washed corundum powder, and nano talc powder in a mass ratio of (44-49):(21-26):(9-14):(7-11):(4-6); the composite binder is compounded from phenolic resin, rosin-modified phenolic resin, water-based acrylic resin, and organosilicon-modified epoxy resin in a mass ratio of (49-54):(26-31):(11-16):(6-9).

2. The coating specifically for V-process casting of manganese steel forklifts according to claim 1, characterized in that, The magnesia powder is fused magnesia powder with an average particle size of 3000-5000 mesh; the mullite powder has an average particle size of 1000-1500 mesh; the andalusite powder has an average particle size of 1200-1800 mesh; the acid-washed capacitor corundum powder is acid-washed capacitor corundum powder W28 with a particle size of 20-28 μm; and the nano talc powder has a particle size of 20-100 nm.

3. The coating specifically for V-process casting of manganese steel forklifts according to claim 1, characterized in that, The phenolic resin is 2130 phenolic resin; the rosin-modified phenolic resin is rosin-modified phenolic resin 221#; the water-based acrylic resin is PChem®BM acrylic resin; and the silicone-modified epoxy resin is HY-1540.

4. The coating specifically for V-process casting of manganese steel forklifts according to claim 1, characterized in that, The composite suspending agent is composed of lithium-based bentonite, organic bentonite, attapulgite, and sepiolite powder in a mass ratio of (39-44):(26-31):(19-24):(6-9).

5. The coating specifically for V-process casting of manganese steel forklifts according to claim 4, characterized in that, The average particle size of the composite suspending agent is 400-800 mesh; the organic bentonite is BENTONE® 34 organic bentonite.

6. The coating specifically for V-process casting of manganese steel forks according to claim 1, characterized in that, The thixotropic agent is a compound of polyvinyl butyral, diatomaceous earth, magnesium aluminum silicate, and fumed silica in a mass ratio of (34-39):(26-31):(21-26):(6-11); the polyvinyl butyral is Mowital™ PVB resin; the fumed silica is hydrophilic with a particle size of 18 nm; the diatomaceous earth has an average particle size of 400-800 mesh; the magnesium aluminum silicate has an average particle size of 500-1000 mesh; the sintering aid is a compound of silica powder, iron oxide red powder, borax powder, and lithium carbonate powder in a mass ratio of (58-63):(24-29):(7-12):(3-6); the sintering aid has an average particle size of 800-1200 mesh.

7. The coating specifically for V-process casting of manganese steel forklifts according to claim 1, characterized in that, The wetting and dispersing aid is composed of polyethylene glycol 600, sodium dodecylbenzene sulfonate, and polycarboxylate dispersant in a mass ratio of (1-2):1:(0.5-1); the polycarboxylate dispersant is SP-S1 polycarboxylate dispersant; the functional modification aid is composed of organic modified montmorillonite and nano titanium dioxide in a mass ratio of (2-3):1; the organic modified montmorillonite is Fenghong DK2 polymer-grade organic clay; the nano titanium dioxide has a particle size of 20 nm; the composite solvent is composed of deionized water, anhydrous ethanol, and propylene glycol methyl ether in a mass ratio of (7-8):1:(0.5-1).

8. A method for preparing a coating specifically for V-process casting of manganese steel forklifts according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Weigh each component of the composite refractory aggregate according to the proportion, mix them and put them into a ball mill. Ball mill at a speed of 220-320 r / min for 2-3 hours, and pass them through a 200-325 mesh sieve to obtain ultrafine composite refractory aggregate powder for later use. Step S2: Weigh the composite binder, wetting and dispersing agent, and functional modifier according to the formula, and add them to 1 / 2-3 / 4 of the mass of the composite solvent. Mix and dissolve the mixture for 16-22 minutes under stirring conditions of 52-62℃ and 320-420r / min. During this period, add the functional modifier in 2-3 portions, and simultaneously use ultrasonic dispersion at 200-300W for 5-8 minutes to obtain the modified binder mixture for later use. Step S3: Weigh out the specified composite suspending agent, thixotropic agent, and sintering aid according to the ratio, and mix them evenly with the ultrafine composite refractory aggregate powder obtained in step S1 to obtain a solid mixed powder for later use. Step S4: Slowly add the solid mixed powder obtained in step S3 to the modified binder mixture obtained in step S2 at a speed of 5-8 kg / min, while stirring at a high speed of 850-1050 r / min for 32-42 min. During the stirring process, add the remaining composite solvent. Step S5: Place the mixture obtained in step S4 into a sand mill and mill for 1-2 hours until the coating particle size D90 ≤ 45μm. Then filter it through a 300-400 mesh sieve to obtain the coating specifically for V-process casting of manganese steel forks.