Spiral spike alloy co-permeation corrosion protection layer and its processing technology

Abstract

The application discloses a spiral stud alloy co-deposition anticorrosion layer and a processing technology thereof. The alloy co-deposition anticorrosion layer comprises a rare earth zinc aluminum co-deposition layer and a sealing layer. The rare earth zinc aluminum co-deposition layer is formed by co-deposition of a co-deposition agent with the following components in parts by weight: zinc powder 40-55 parts, zinc aluminum powder 15-30 parts, zinc aluminum magnesium silicon powder 15-25 parts, and a permeation aid 1-15 parts. The sealing layer is formed by drying an aqueous sealing agent with the following components in parts by weight: aqueous acrylic resin 100 parts, dimethyl ethanolamine (DMEA) 3-4 parts, water-soluble acrylic modified polyester resin 8-12 parts, composite molybdate aqueous solution 45-55 parts, wetting dispersant 8-12 parts, defoaming agent 8-12 parts, filler 12-16 parts, and ultraviolet light absorber 1-3 parts.

Description

Technical Field

[0001] This invention belongs to the field of metal surface chemical heat treatment technology, specifically relating to a spiral rail spike alloy co-permeation anti-corrosion layer and its processing technology. Background Technology

[0002] Railway elastic rail fasteners are key components in railway track systems used to secure the connection between rails and sleepers (or track slabs). Their main functions include maintaining rail position, providing elastic cushioning, insulation, and adjusting track gauge. Type II fasteners are primarily used on passenger and freight railways, with core fastening and clamping components including the Type II elastic rail, spiral spikes, nuts, and flat washers. Spiral spikes used in highly corrosive environments such as coastal areas and tunnels are exposed to complex environments including humidity, rainfall, polluted gases, and acid / alkali / salt solutions, which accelerates corrosion. Corrosion leads to surface rust, reduced effective cross-sectional area, decreased mechanical properties, and even potential breakage, posing safety hazards. In severe cases of corrosion, the spike diameter can shrink from 24mm to approximately 10mm, making it highly susceptible to breakage.

[0003] Currently, the anti-corrosion treatment of railway spiral spikes mainly falls into three categories: surface coating technology, chemical heat treatment technology, and combined reinforcement technology. Surface coating technology includes galvanizing, Dacromet / zinc-chromium coating, and oiling; chemical heat treatment technology includes zinc diffusion and multi-element co-diffusion; and combined reinforcement technology involves layering a sealing layer or rust-preventive oil on top of the base coating. In addition to considering the high corrosion resistance and long service life requirements of the anti-corrosion layer, the anti-corrosion protection of spiral spikes must also consider the thread fit accuracy requirements. Excessive anti-corrosion layer thickness may affect the screwing.

[0004] Multi-element co-diffusion is a process in which nitrogen, carbon, rare earth elements, and other elements are simultaneously diffused into the surface of steel at high temperatures, forming a compound layer that is firmly bonded to the matrix. This results in excellent corrosion resistance and wear resistance, enabling maintenance-free operation and a long service life. Chinese invention patent application CN112126892A (published on December 25, 2020), entitled "A Multi-element Alloy Co-diffusion Agent for Improving the Wear Resistance of Steel and Its Application," discloses a multi-element alloy co-diffusion agent that can improve the wear resistance of steel workpieces. By weight, the multi-element alloy co-diffusion agent comprises: 40-55 parts zinc powder, 20-30 parts zinc-aluminum powder, 10-20 parts aluminum-magnesium powder, 5-10 parts zinc-chromium-silicon alloy powder, and 5-10 parts zinc-manganese-silicon alloy powder. The mixture comprises 0.1-1.5 parts of mixed rare earth elements and 0.4-1 parts of a penetration enhancer. Based on the weight of the zinc-aluminum powder, aluminum accounts for 7%-11%, with the balance being zinc. In the aluminum-magnesium powder, aluminum accounts for 45%-55%, with the balance being magnesium. In the zinc-chromium-silicon alloy powder, zinc accounts for 75%-90%, chromium for 5%-15%, and the balance is silicon. In the zinc-manganese-silicon alloy powder, zinc accounts for 75%-90%, manganese for 5%-15%, and the balance is silicon. The mixed rare earth elements include lanthanum oxide and cerium oxide. The spiral rail spike thread consists of a coarse thread and a fine thread. The fine thread is installed with a nut, while the coarse thread is pre-embedded with grout and connected to the concrete sleeper. Therefore, the anti-corrosion layer on the spiral rail spike thread and the exposed rail spike member needs to consider wear resistance, resistance to external media abrasion and impact, long-term corrosion resistance, and weather resistance. However, CN112126892A does not mention the weather resistance of the penetration layer. Therefore, there is a need for an anti-corrosion coating that is suitable for the exposed parts of the spiral rail spikes, especially for long-term service in highly corrosive environments. Summary of the Invention

[0005] Overcoming the shortcomings of existing technologies, this invention provides an alloy co-permeation anti-corrosion layer for spiral railway spikes. This anti-corrosion layer possesses properties such as wear and impact resistance, high hardness, and long resistance to neutral salt spray. Besides spiral railway spikes, the anti-corrosion layer and its processing technology of this invention can also be used for other components of railway elastic clip fasteners, such as nuts, gauge blocks, elastic clips, and flat washers, thereby significantly improving the service performance of metal components in railway fasteners.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0007] A spiral rail spike alloy co-diffusion anti-corrosion layer includes a rare earth zinc-aluminum co-diffusion layer and a sealing layer, wherein the rare earth zinc-aluminum co-diffusion layer is formed by co-diffusion of a co-diffusion agent having the following weight parts:

[0008] 40-55 parts zinc powder, 15-30 parts zinc-aluminum powder, 15-25 parts zinc-aluminum-magnesium-silicon powder, and 1-15 parts penetration enhancer;

[0009] Based on the mass of the zinc-aluminum powder as 100%, aluminum accounts for 4.7% to 6.2%, mixed rare earth elements account for 0.03% to 0.1%, and the balance is Zn;

[0010] Based on the mass of the zinc-aluminum-magnesium-silicon powder as 100%, aluminum accounts for 10%~12%, Mg accounts for 2%~4%, Si accounts for 0.1%~0.3%, mixed rare earth accounts for 0.03%~0.1%, and the balance is Zn;

[0011] In the zinc-aluminum powder and zinc-aluminum-magnesium-silicon powder, the mixed rare earth is lanthanum oxide and cerium oxide in a mass ratio of 1:1.

[0012] Preferably, the particle size of the zinc powder, zinc-aluminum powder, and zinc-aluminum-magnesium-silicon powder is independently 200-400 mesh.

[0013] The zinc powder, zinc-aluminum powder, and zinc-aluminum-magnesium-silicon powder can all be commercially available products.

[0014] As an alternative implementation, the zinc-aluminum powder and the zinc-aluminum-magnesium-silicon powder can be prepared by the following process steps:

[0015] I. Add the alloy ingots that meet the proportions to the melting furnace, heat to 750~880℃, and after they are completely melted, stir thoroughly, keep warm for 15~30 minutes, remove the surface slag, and obtain the alloy liquid;

[0016] II. In the atomizing tank, high-purity argon gas with a pressure of not less than 0.9 MPa is sprayed at a speed of 250~350 m / s to the alloy liquid obtained in step I. The direction of argon gas spraying is 90° with the direction of alloy liquid flow, so that the alloy liquid is atomized into micro-droplets. After being cooled by a condenser, dried, and sieved, alloy powder with a particle size of 200~400 mesh is obtained.

[0017] Preferably, the penetration aid is ammonium chloride and one selected from quartz sand and alumina, and ammonium chloride accounts for 90% of the penetration aid by mass of 100%.

[0018] Preferably, the particle size of aluminum oxide and quartz sand is independently 20-70 mesh.

[0019] Preferably, the sealing layer is formed by drying an aqueous sealing agent having the following weight composition:

[0020] 100 parts of waterborne acrylic resin, 3-4 parts of dimethylethanolamine (DMEA), 8-12 parts of water-soluble acrylic modified polyester resin, 45-55 parts of composite molybdate aqueous solution, 8-12 parts of wetting and dispersing agent, 8-12 parts of defoamer, 12-16 parts of filler, and 1-3 parts of ultraviolet light absorber.

[0021] Preferably, the sealing layer is formed by drying an aqueous sealing agent having the following components by weight:

[0022] 100 parts of waterborne acrylic resin, 3.5 parts of dimethylethanolamine (DMEA), 10 parts of water-soluble acrylic modified polyester resin, 50 parts of composite molybdate aqueous solution, 10 parts of wetting and dispersing agent, 10 parts of defoamer, 14.5 parts of filler, and 2 parts of ultraviolet light absorber.

[0023] The waterborne acrylic resin is a commercially available product, such as NeoCryl A614 manufactured by Covestro in Germany.

[0024] Preferably, the water-soluble acrylic modified polyester resin can be a commercially available product, such as water-soluble acrylic modified polyester resin 799 produced by Changzhou Sisai New Material Technology Co., Ltd.

[0025] Preferably, based on the mass of the composite molybdate aqueous solution being 100%, the composition of the composite molybdate aqueous solution is as follows:

[0026] The mixture consists of 1%–5% water-soluble molybdate, 5%–15% acetic acid, 5%–15% coupling agent, 5%–15% ethanol, and the balance being water.

[0027] Preferably, the water-soluble molybdate is selected from sodium molybdate, potassium molybdate, ammonium molybdate, and magnesium molybdate.

[0028] Preferably, the coupling agent is tetraisopropyl di(dioctylphosphite)titanate.

[0029] As a preferred embodiment, the composite molybdate aqueous solution is prepared by the following method:

[0030] A. Prepare the raw materials according to the stated mass percentage ratio;

[0031] B. Dissolve acetic acid in water and stir until homogeneous to obtain solution I;

[0032] C. Mix the coupling agent and ethanol, stir until completely dissolved, add the solution I obtained in step B, stir evenly to obtain solution II;

[0033] D. Add water-soluble molybdate to solution II and stir until completely dissolved to obtain the final product.

[0034] Preferably, the ultraviolet absorber is N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidinium, the wetting and dispersing agent is polyethylene glycol, the defoamer is polydimethylsiloxane, and the filler is kaolin.

[0035] As a preferred embodiment, the aqueous sealant is prepared by a preparation method comprising the following steps:

[0036] ① Prepare each component according to the stated weight proportions;

[0037] ② In a mixing device equipped with a stirring device, first add water-based acrylic resin, then add dimethylethanolamine and the aqueous solution of the composite molybdate in sequence, stir evenly, and adjust the pH value to 8.5~10.0 to obtain an aqueous acrylic resin emulsion;

[0038] ③ While stirring, add wetting and dispersing agent, part of the defoamer and all of the filler to the water-based acrylic resin emulsion obtained in step ② in sequence, stir evenly to obtain slurry;

[0039] ④ Grind the slurry to a fineness of less than 45μm using a sand mill, and control the temperature of the mill to not exceed 60℃ during the grinding process; add water-soluble acrylic modified polyester resin, ultraviolet light absorber and the remaining defoamer to the ground slurry in sequence, and stir evenly to obtain the final product.

[0040] Preferably, the preparation method of the aqueous sealant may further include the following steps after step ④:

[0041] ⑤ Adjust the color and gloss of the sealant, and then filter it through a 120-mesh filter.

[0042] Preferably, in step ②, dimethylethanolamine is slowly added at a speed of 500 r / min, and after stirring evenly, the speed is increased to 900 r / min, and the composite molybdate aqueous solution is added.

[0043] Preferably, in step ③, the wetting and dispersing agent and the defoamer are added sequentially at a rotation speed of 500 r / min, and then the rotation speed is increased to 800 r / min, and the filler is added until the mixture is homogeneous.

[0044] Preferably, in step ⑤, according to color card number 2333U, a colorimeter is used for calibration, and water-based pigments are used to adjust the color to match the color card; matting powder is used to adjust the gloss to meet the requirements.

[0045] Preferably, the co-permeation layer has a thickness of 50 μm or more, and the sealing layer has a thickness of 20 μm-30 μm.

[0046] Another objective of this invention is to provide a processing technology for the spiral rail spike alloy co-permeation anti-corrosion layer described herein, comprising:

[0047] I. Workpiece Surface Treatment

[0048] The spiral rail spikes are sequentially carbonized and degreased, and shot blasted to achieve a surface roughness of Sa2.5 or higher, and are then ready for use.

[0049] II. Multi-element co-permeation

[0050] Mix the co-diffusion agent evenly according to the specified ratio and place it in a co-diffusion furnace. The mass ratio of the co-diffusion agent to the co-diffusion furnace volume is (60kg~80kg):100L. Embed the spiral rail spikes treated in step I in the co-diffusion agent. The mass ratio of the co-diffusion agent to the spiral rail spikes is (40kg~50kg):1000kg. Turn on the power, set the co-diffusion furnace rotation speed to 2~4r / min, furnace pressure to 0.1Pa, and maintain a temperature of 370℃~400℃ for 5~8 hours. Stop heating, maintain the rotation speed until the furnace temperature drops below 100℃, then push out the furnace chamber for natural cooling, open the furnace cover, and separate the workpiece from the furnace charge.

[0051] III. Formation of a closed layer

[0052] After co-infiltration treatment, the spiral track spikes are rinsed with water, air-dried, and then immersed in the sealant for 20-30 seconds. After removal, they are dried at 100-140°C for at least 30 minutes to obtain the final product.

[0053] Preferably, the interval between step I and step II shall not exceed 1 hour.

[0054] Preferably, in step II, the co-infiltration furnace is heated to 390℃~410℃ and held for 5~7 hours.

[0055] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0056] (1) Zinc-aluminum powder and zinc-aluminum-magnesium-silicon powder containing rare earth elements improve the scratch resistance of the diffusion layer. The metallographic structure shows a striped zinc-aluminum-magnesium eutectic structure. The introduction of Si and rare earth elements increases the corrosion resistance of the diffusion layer.

[0057] (2) The sealing layer formed by the water-based sealant further improves the density and corrosion resistance of the penetration layer, the titanate coupling agent increases the bonding force between the weather-resistant acrylic resin and the substrate, and the ultraviolet absorber improves the weather resistance of the coating.

[0058] (3) The production process of water-based sealants is pollution-free and meets the requirements of green environmental protection.

[0059] (4) The co-permeation layer and the sealing layer are over 70μm thick, which have high corrosion resistance, weather resistance and scratch resistance, making them the best choice for anti-corrosion processing of metal parts of track fasteners. At the same time, the presence of the co-permeation layer and the sealing layer does not affect the screwing of the track spike.

[0060] (5) The cold bending and tensile properties of the alloy co-permeable anti-corrosion spiral road studs meet the requirements of the current standards.

[0061] Those skilled in the art should understand that the alloy co-diffusion anti-corrosion layer comprising a rare-earth zinc-aluminum co-diffusion layer and a sealing layer described in this invention is not limited to spiral rail spikes, but can also be applied to other metal components of railway elastic clip fasteners, including but not limited to nuts, gauge plates, elastic clips, and flat washers. Tests have shown that elastic clips treated with the multi-element co-diffusion and sealing layer described in this invention can withstand 10 million fatigue cycles without fracture, and their mechanical and corrosion resistance properties are superior to those of existing zinc-diffusion technologies. Furthermore, the alloy co-diffusion anti-corrosion layer described in this invention can also be applied to other metal components with high corrosion resistance and long service life requirements.

[0062] In this application, the number of "parts by weight" refers to the mass ratio between the relevant components, rather than the actual mass. Depending on the actual situation, 1 part by weight can be any mass, such as 1g, 10g, 250g, 500g, 1kg, 1 ton, etc. Detailed Implementation

[0063] The present invention will be described below with reference to specific embodiments. Those skilled in the art will understand that these embodiments are for illustrative purposes only and do not limit the scope of the invention in any way.

[0064] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all raw materials, reagents, and other materials used in the following examples are commercially available products. Specifically:

[0065] Zinc-aluminum alloy ingot: Galfan alloy, provided by Hunan Rare Earth Metal Materials Research Institute; based on the mass of Galfan alloy as 100%, aluminum accounts for 4.7%~6.2%, mixed rare earth accounts for 0.03%~0.1%, and the balance is Zn;

[0066] Zinc-aluminum-magnesium-silicon rare earth alloy ingots: provided by Hunan Rare Earth Metal Materials Research Institute; based on the mass of the zinc-aluminum-magnesium-silicon rare earth alloy ingots as 100%, aluminum accounts for 10%~12%, Mg accounts for 2%~4%, Si accounts for 0.1%~0.3%, mixed rare earth accounts for 0.03%~0.1%, and the balance is Zn;

[0067] In the Galfan alloy ingot and the zinc-aluminum-magnesium-silicon rare earth alloy ingot, the mixed rare earth is selected from lanthanum oxide and cerium oxide in a mass ratio of 1:1.

[0068] Zinc-aluminum powder or zinc-aluminum-magnesium-silicon powder is prepared by the following steps:

[0069] I. Add the alloy ingot to the melting furnace, heat it to 750~880℃, and after it is completely melted, stir it thoroughly, keep it at the temperature for 15~30 minutes, remove the surface slag, and obtain the alloy liquid;

[0070] II. In the atomizing tank, high-purity argon gas with a pressure of not less than 0.9 MPa is sprayed at a speed of 250~350 m / s to the alloy liquid obtained in step I. The direction of argon gas spraying is 90° with the direction of alloy liquid flow, so that the alloy liquid is atomized into micro-droplets. After being cooled by a condenser, dried, and sieved, alloy powder with a particle size of 200~400 mesh is obtained.

[0071] Quartz sand: Produced by Quyang Quartz Sand Factory, Baoding City, Hebei Province; Particle size 0.6mm-0.8mm (24-30 mesh).

[0072] Aluminum oxide: Produced by Shijiazhuang Jinghuang Technology Co., Ltd., particle size 0.6mm-0.8mm (24-30 mesh). Ammonium chloride: Produced by Tianjin Jinyaoxiangcheng Technology Co., Ltd.

[0073] Waterborne acrylic resin: NeoCryl A614, manufactured by Covestro, Germany.

[0074] Dimethylethanolamine: Produced by Jinan Juxinbangshi New Materials Co., Ltd.

[0075] Water-soluble acrylic modified polyester resin: produced by Changzhou Sisai New Material Technology Co., Ltd., grade 799.

[0076] Polydimethylsiloxane: Produced by Jinan Juxinbangshi New Material Co., Ltd.

[0077] Kaolin: Produced by Tianjin Jinyaoxiangcheng Technology Co., Ltd.

[0078] N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidinium: Produced by Jinan Juxinbangshi New Materials Co., Ltd.

[0079] Sodium molybdate: Produced by Jinan Juxinbangshi New Materials Co., Ltd.

[0080] Tetraisopropyl di(dioctylphosphite) titanate: Produced by Jinan Juxinbangshi New Materials Co., Ltd.

[0081] Examples 1-5

[0082] A rare earth zinc-aluminum co-diffusion layer is formed on the surface of a 60-rail Type II spiral rail spike through thermal co-diffusion using the following process steps:

[0083] I. Workpiece Surface Treatment

[0084] The spiral rail spikes are first degreased by carbonization, then shot blasted with steel shot with a diameter of 0.1-0.3 mm to achieve a surface roughness of Sa2.5 or higher, and then set aside for use; step II is carried out within 1 hour.

[0085] II. Multi-element co-permeation

[0086] Mix the components of the co-diffusion agent evenly according to the proportions shown in Table 1, and place them in a co-diffusion furnace. The mass ratio of the co-diffusion agent to the co-diffusion furnace volume is (60kg~80kg):100L. Embed the spiral track spikes treated in step I in the co-diffusion agent. The mass ratio of the co-diffusion agent to the spiral track spikes is (40kg~50kg):1000kg. Turn on the power, set the co-diffusion furnace rotation speed to 2~4r / min, furnace pressure to 0.1Pa, and maintain a temperature of 370℃~400℃ for 5~8 hours (the specific holding temperatures and holding times for each embodiment are shown in Table 1). Stop heating, maintain the rotation speed until the furnace temperature drops below 100℃, remove the furnace chamber for natural cooling, open the furnace lid, and separate the workpiece from the furnace charge. Spray the workpiece with water to clean it, and then dry it.

[0087] The performance of the rare earth zinc-aluminum co-diffusion layer on the surface of the spiral rail spike was determined using the following methods:

[0088] The hardness of the co-permeable layer shall be determined in accordance with GB / T4340.1, the thickness of the co-permeable layer shall be determined in accordance with GB / T4956, the neutral salt spray resistance time of the co-permeable layer shall be determined in accordance with GB / T10125, and the neutral salt spray resistance time of the co-permeable layer after crisscrossing shall be determined in accordance with GB / T31586.2.

[0089] The measurement results are shown in Table 1.

[0090] Comparative Examples 1-4

[0091] Following the basic process steps of Examples 1-5, the same type of spiral rail spikes as those in Examples 1-5 were subjected to thermal co-diffusion treatment to obtain spiral rail spikes with a rare earth zinc-aluminum co-diffusion layer on the surface; the difference is that the co-diffusion agents used in Comparative Examples 1-4 are different, as shown in Table 1.

[0092] The corrosion resistance of the rare earth zinc-aluminum co-diffusion layers of Comparative Examples 1-4 was determined using the same method as in Example 1, and the results are shown in Table 1.

[0093]

[0094] Comparative Example 1 did not use zinc-aluminum-magnesium-silicon powder, Comparative Example 2 used only zinc-aluminum powder, Comparative Example 3 used only zinc-aluminum-magnesium-silicon powder, and Comparative Example 4 used a relatively low amount of zinc-aluminum-magnesium-silicon powder. The hardness of the infiltrated layers obtained in Comparative Examples 1 to 4 was low; the time for red rust to appear after neutral salt spray and after scratching was less than 1000 hours, and the corrosion resistance was significantly inferior to the co-infiltrated layer of the present invention.

[0095] Examples 6-10

[0096] The spiral rail spikes treated with co-infiltration in Examples 1-5 were rinsed with water, air-dried, and then immersed in a sealant for 20-30 seconds. The spiral rail spikes were then removed and dried at 100-140°C for 30 minutes.

[0097] The composition of the sealing agent used in Examples 6-10 is as follows (wherein, 1 part by weight = 100 kg):

[0098] Water-based acrylic resin: 100 parts

[0099] Dimethylethanolamine: 3.5 parts,

[0100] Water-soluble acrylic-modified polyester resin: 10 parts

[0101] Wetting and dispersing agent: Polyethylene glycol (CAS No.: 25322-68-3, molecular weight 697), 10 parts.

[0102] Defoamer: Polydimethylsiloxane, 10 parts

[0103] Filler: Kaolin, 14.5 parts

[0104] UV absorber: N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidin, 2 parts.

[0105] 50 parts of a composite molybdate aqueous solution were prepared by the following method:

[0106] A. Prepare the raw materials according to the proportions shown in Table 2;

[0107] B. Dissolve acetic acid in water and stir until homogeneous to obtain solution I;

[0108] C. Mix the coupling agent and ethanol, stir until completely dissolved, add the solution I obtained in step B, stir evenly to obtain solution II;

[0109] D. Add sodium molybdate to solution II and stir until completely dissolved to obtain the final product.

[0110] The performance of the sealing layer was determined using the following method:

[0111] The hardness of the sealing layer shall be determined in accordance with GB / T4340.1, the adhesion of the sealing layer shall be determined in accordance with GB / T5210, the damp heat resistance test of the acute sealing layer shall be conducted in accordance with GB / T1740, and the UV aging resistance test shall be conducted in accordance with GB / T14522.

[0112] The measurement results are shown in Table 2.

[0113] Comparative Examples 5-7

[0114] The spiral rail spikes treated with co-infiltration in Example 4 were rinsed with water, air-dried, and then immersed in a sealant for 20-30 seconds. The spiral rail spikes were then removed and dried at 100-140°C for 30 minutes.

[0115] The composition of the sealing agents used in Comparative Examples 5-7 is basically the same as that of the sealing agent in Example 6, except for the composition of the composite molybdate aqueous solution. The composition of the composite molybdate aqueous solution contained in the sealing agents used in Comparative Examples 5-7 is shown in Table 2.

[0116] The sealing layers of Comparative Examples 5-7 were measured using the same method as in Example 6, and the results are shown in Table 2.

[0117] Comparative Example 8

[0118] The spiral rail spikes treated with co-infiltration in Example 4 were rinsed with water, air-dried, and then immersed in a sealant for 20-30 seconds. The spiral rail spikes were then removed and dried at 100-140°C for 30 minutes.

[0119] The composition of the sealing agent used in Comparative Example 8 is as follows (where 1 part by weight = 100 kg):

[0120] Water-based acrylic resin: 110 parts

[0121] Dimethylethanolamine: 3.5 parts,

[0122] Water-soluble acrylic-modified polyester resin: 0 parts

[0123] Wetting and dispersing agent: Polyethylene glycol (CAS No.: 25322-68-3, molecular weight 697), 10 parts.

[0124] Defoamer: Polydimethylsiloxane, 10 parts

[0125] Filler: Kaolin, 14.5 parts

[0126] Ultraviolet light absorber: N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidinium, 2 parts;

[0127] 50 parts of a composite molybdate aqueous solution were prepared by the following method:

[0128] A. Prepare the raw materials according to the proportions shown in Table 2;

[0129] B. Dissolve acetic acid in water and stir until homogeneous to obtain solution I;

[0130] C. Mix the coupling agent and ethanol, stir until completely dissolved, add the solution I obtained in step B, stir evenly to obtain solution II;

[0131] D. Add sodium molybdate to solution II and stir until completely dissolved to obtain the final product.

[0132] The sealing layer of Comparative Example 8 was measured using the same method as in Example 6, and the results are shown in Table 2.

[0133]

[0134] The composite molybdate aqueous solution of Comparative Example 5 did not contain silane coupling agent, while the composite molybdate aqueous solution of Comparative Example 7 had an excessively high silane coupling agent content. The sealing agent of Comparative Example 6 did not contain molybdate, and the sealing agent of Comparative Example 8 did not contain water-soluble acrylic-modified polyester resin. The sealing layers obtained in Comparative Examples 5 to 8 all had low adhesion, and their damp heat resistance test time and UV aging resistance were both less than 1000 hours, indicating that their weather resistance was significantly inferior to that of the sealing layer of the present invention.

[0135] In summary, this invention provides a machining process for an alloy co-diffusion anti-corrosion layer. The alloy co-diffusion anti-corrosion layer comprises a rare-earth zinc-aluminum co-diffusion layer and a sealing layer, and is particularly suitable for the anti-corrosion treatment of railway track spikes. Of course, the anti-corrosion layer and its machining process of this invention can also be used for other components of railway elastic clip fasteners, such as nuts, gauge blocks, elastic clips, and flat washers, thereby significantly improving the service performance of railway fastener metal components.

Claims

1. A spiral rail spike alloy co-diffusion anti-corrosion coating, comprising a rare earth zinc-aluminum co-diffusion layer and a sealing layer, wherein, The rare earth zinc-aluminum co-diffusion layer is formed by co-diffusion of a co-diffusion agent having the following weight parts: 40-55 parts zinc powder, 15-30 parts zinc-aluminum powder, 15-25 parts zinc-aluminum-magnesium-silicon powder, and 1-15 parts penetration enhancer; Based on the mass of the zinc-aluminum powder as 100%, aluminum accounts for 4.7% to 6.2%, mixed rare earth elements account for 0.03% to 0.1%, and the balance is Zn; Based on the mass of the zinc-aluminum-magnesium-silicon powder as 100%, aluminum accounts for 10%~12%, Mg accounts for 2%~4%, Si accounts for 0.1%~0.3%, mixed rare earth accounts for 0.03%~0.1%, and the balance is Zn; In the zinc-aluminum powder and zinc-aluminum-magnesium-silicon powder, the mixed rare earth is lanthanum oxide and cerium oxide in a mass ratio of 1:

1.

2. The alloy co-diffusion anti-corrosion layer according to claim 1, characterized in that, The particle size of the zinc powder, zinc-aluminum powder, and zinc-aluminum-magnesium-silicon powder is independently 200~400 mesh; Optionally, the zinc-aluminum powder and the zinc-aluminum-magnesium-silicon powder can be prepared by the following process steps: I. Add the alloy ingots that meet the proportions to the melting furnace, heat to 750~880℃, and after they are completely melted, stir thoroughly, keep warm for 15~30 minutes, remove the surface slag, and obtain the alloy liquid; II. In the atomizing tank, high-purity argon gas with a pressure of not less than 0.9 MPa is sprayed at a speed of 250~350 m / s to the alloy liquid obtained in step I. The direction of argon gas spraying is 90° with the direction of alloy liquid flow, so that the alloy liquid is atomized into micro-droplets. After being cooled by a condenser, dried, and sieved, alloy powder with a particle size of 200~400 mesh is obtained.

3. The alloy co-diffusion anti-corrosion layer according to claim 1, characterized in that, The penetration aid is ammonium chloride and one selected from quartz sand and alumina, wherein ammonium chloride accounts for 90% of the penetration aid by mass of 100%. Preferably, the particle size of aluminum oxide and quartz sand is independently 20-70 mesh.

4. The alloy co-diffusion anti-corrosion layer according to claim 1, characterized in that, The sealing layer is formed by drying an aqueous sealing agent having the following weight composition: 100 parts of waterborne acrylic resin, 3-4 parts of dimethylethanolamine (DMEA), 8-12 parts of water-soluble acrylic modified polyester resin, 45-55 parts of composite molybdate aqueous solution, 8-12 parts of wetting and dispersing agent, 8-12 parts of defoamer, 12-16 parts of filler, and 1-3 parts of ultraviolet light absorber. Preferably, the sealing layer is formed by drying an aqueous sealing agent having the following components by weight: 100 parts of waterborne acrylic resin, 3.5 parts of dimethylethanolamine (DMEA), 10 parts of water-soluble acrylic modified polyester resin, 50 parts of composite molybdate aqueous solution, 10 parts of wetting and dispersing agent, 10 parts of defoamer, 14.5 parts of filler, and 2 parts of ultraviolet light absorber.

5. The alloy co-diffusion anti-corrosion layer according to claim 4, characterized in that, Based on the mass of the composite molybdate aqueous solution being 100%, the composition of the composite molybdate aqueous solution is as follows: 1%–5% water-soluble molybdate, 5%–15% acetic acid, 5%–15% coupling agent, 5%–15% ethanol, and the balance being water; Preferably, the water-soluble molybdate is selected from sodium molybdate, potassium molybdate, ammonium molybdate, and magnesium molybdate; Preferably, the coupling agent is tetraisopropyl di(dioctylphosphite)titanate; Preferably, the composite molybdate aqueous solution is prepared by the following method: A. Prepare the raw materials according to the stated mass percentage ratio; B. Dissolve acetic acid in water and stir until homogeneous to obtain solution I; C. Mix the coupling agent and ethanol, stir until completely dissolved, add the solution I obtained in step B, stir evenly to obtain solution II; D. Add water-soluble molybdate to solution II and stir until completely dissolved to obtain the final product; Preferably, the ultraviolet absorber is N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidinium, the wetting and dispersing agent is polyethylene glycol, the defoamer is polydimethylsiloxane, and the filler is kaolin.

6. The alloy co-diffusion anti-corrosion layer according to claim 4 or 5, characterized in that, The aqueous sealant is prepared by a method comprising the following steps: ① Prepare each component according to the stated weight proportions; ② In a mixing device equipped with a stirring device, first add water-based acrylic resin, then add dimethylethanolamine and the aqueous solution of the composite molybdate in sequence, stir evenly, and adjust the pH value to 8.5~10.0 to obtain an aqueous acrylic resin emulsion; ③ While stirring, add wetting and dispersing agent, part of the defoamer and all of the filler to the water-based acrylic resin emulsion obtained in step ② in sequence, stir evenly to obtain slurry; ④ Grind the slurry to a fineness of less than 45μm using a sand mill, and control the temperature of the mill to not exceed 60℃ during the grinding process; add water-soluble acrylic modified polyester resin, ultraviolet light absorber and the remaining defoamer to the ground slurry in sequence, and stir evenly to obtain the final product; Preferably, the preparation method of the aqueous sealant may further include the following steps after step ④: ⑤ Adjust the color and gloss of the sealant, and then filter it through a 120-mesh filter.

7. The alloy co-diffusion anti-corrosion layer according to claim 6, characterized in that, In step ②, dimethylethanolamine is slowly added at a speed of 500 r / min, and after stirring evenly, the speed is increased to 900 r / min, and the composite molybdate aqueous solution is added. Preferably, in step ③, the wetting and dispersing agent and the defoamer are added sequentially at a rotation speed of 500 r / min, and then the rotation speed is increased to 800 r / min, and the filler is added until the mixture is homogeneous; Preferably, in step ⑤, according to color card number 2333U, a colorimeter is used for calibration, and water-based pigments are used to adjust the color to match the color card; matting powder is used to adjust the gloss to meet the requirements.

8. The alloy co-diffusion anti-corrosion coating according to any one of claims 1 to 7, characterized in that, The co-permeation layer has a thickness of 50 μm or more, and the sealing layer has a thickness of 20 μm to 30 μm.

9. The processing technology of the spiral rail spike alloy co-permeation anti-corrosion coating according to any one of claims 1 to 8, comprising: I. Workpiece Surface Treatment The spiral rail spikes are sequentially carbonized and degreased, and shot blasted to achieve a surface roughness of Sa2.5 or higher, and are then ready for use. II. Multi-element co-osmosis Mix the co-diffusion agent evenly according to the specified ratio and place it in a co-diffusion furnace. The mass ratio of the co-diffusion agent to the co-diffusion furnace volume is (60kg~80kg):100L. Embed the spiral rail spikes treated in step I in the co-diffusion agent. The mass ratio of the co-diffusion agent to the spiral rail spikes is (40kg~50kg):1000kg. Turn on the power, set the co-diffusion furnace rotation speed to 2~4r / min, furnace pressure to 0.1Pa, and maintain a temperature of 370℃~400℃ for 5~8 hours. Stop heating, maintain the rotation speed until the furnace temperature drops below 100℃, then push out the furnace chamber for natural cooling, open the furnace cover, and separate the workpiece from the furnace charge. III. Formation of a closed layer After co-infiltration treatment, the spiral track spikes are rinsed with water, air-dried, and then immersed in the sealant for 20-30 seconds. After removal, they are dried at 100-140°C for at least 30 minutes to obtain the final product.

10. The processing technology according to claim 9, characterized in that, The interval between Step I and Step II shall not exceed 1 hour; Preferably, in step II, the co-infiltration furnace is heated to 390℃~410℃ and held for 5~7 hours.

Images