A permeation aid and co-permeation agent for corrosion protection of metal members

Abstract

A kind of for metal member anticorrosion of permeation aid and co-permeation agent, the permeation aid includes potassium fluoborate and ammonium chloride;Potassium fluoborate is 8-9 parts by weight, and ammonium chloride is 1-2 parts by weight;Co-permeation agent includes the permeation aid, multi-element metal powder and dispersant;Multi-element metal powder includes zinc powder, zinc-aluminum alloy powder, magnesium-aluminum alloy powder, rare earth oxide by weight parts;Multi-element metal powder includes zinc powder 60-70 parts by weight, zinc-aluminum powder 30-35 parts by weight, magnesium-aluminum powder 1-5 parts by weight, and rare earth oxide 0.5-1.0 parts by weight.The anticorrosion permeation layer formed on the surface of the component by the multi-element alloy co-permeation process using the novel permeation aid provided by the application can significantly improve the corrosion resistance of steel components.

Description

Technical Field

[0001] This invention relates to the field of metal corrosion protection technology, and in particular to a penetration enhancer and a co-penetrating agent for corrosion protection of metal components. Background Technology

[0002] To prevent corrosion damage to metal components, scholars both domestically and internationally have conducted long-term research on anti-corrosion technologies. Among these, multi-element powder co-infiltration technology for metal components has been continuously innovated, including electroplating, hot-dip galvanizing, and Dacromet technology. However, these technologies all have shortcomings in practical applications. Electroplating limits the volume of the workpiece due to the electroplating tank, resulting in a thinner coating. Improper treatment can lead to hydrogen embrittlement, reducing the workpiece's hardness, and also causes pollution from the emission of waste gas, wastewater, and solid waste. Hot-dip galvanizing results in a thicker coating, making it difficult to control dimensions and uniformity, and also generates pollution from zinc waste and steam. Dacromet treatment suffers from insufficient adhesion between the substrate and the film layer, resulting in poor wear resistance. Furthermore, it involves high processing temperatures and high costs, and some methods also produce hexavalent chromium, causing serious environmental pollution. Therefore, these methods have been successively restricted and phased out by industry.

[0003] Multi-element alloy co-diffusion technology involves placing multi-element micro-nano zinc diffusion agents and metal components in a vacuum zinc diffusion furnace and heating them to a certain temperature. Multi-element active metal atoms penetrate from the surface of the component into the interior, while iron elements inside the component diffuse from the inside out. By utilizing the principles of physical and chemical adsorption deposition and mechanical collision, multi-element metal powder forms a diffusion layer on the surface of the workpiece. It is a gradually emerging and highly efficient anti-corrosion technology for metal components, which can effectively improve the service life of the substrate.

[0004] Many factors influence the multi-element powder co-infiltration technology for metal components, including the zinc infiltration raw materials and the zinc infiltration process. Zinc infiltration raw materials include metal powders, alloy powders, powders, and infiltration aids; while the zinc infiltration process includes factors such as temperature and holding time. Among these, the zinc infiltration formulation is crucial, and the selection of infiltration aids directly affects the final effect of powder zinc infiltration. Therefore, optimizing the design of infiltration aid formulations and optimizing zinc infiltration process parameters have become the main research directions for multi-element powder co-infiltration of metal components. In novel composite corrosion protection technologies, powder zinc infiltration is a critical step, especially in exploring the effect of multi-element powder co-infiltration under the action of infiltration aids. This invention proposes a novel infiltration aid formulation and process, significantly improving the co-infiltration effect. Summary of the Invention

[0005] The purpose of this invention is to solve the aforementioned problems in the prior art and provide a penetration aid and a co-penetrating agent for corrosion protection of metal components. Utilizing the activated boron atoms in the penetration aid, the surface self-cleaning properties of fluoroboric acid, and the reaction mechanism of ammonium chloride, a zinc-penetrating layer is formed on the surface of the metal component. This zinc-penetrating layer is formed by the co-penetrating agent, which comprises anti-corrosion metal powder, a dispersant, and the penetration aid, in contact with the metal component at high temperatures. This invention can effectively increase the thickness of the penetration layer, the effective absorption rate of the penetration agent, and improve the uniformity of the penetration layer surface. It provides an excellent corrosion protection solution for structural materials used in the construction of special roads such as high-speed railways while controlling material costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A penetration enhancer for corrosion protection of metal components, the penetration enhancer comprising potassium fluoroborate and ammonium chloride.

[0008] By weight, potassium fluoroborate is 8-9 parts and ammonium chloride is 1-2 parts.

[0009] A co-permeation agent for corrosion protection of metal components includes the aforementioned permeation aid, and further includes multi-element metal powder and a dispersant.

[0010] By weight, the multi-element metal powder includes zinc powder, zinc-aluminum alloy powder, magnesium-aluminum alloy powder, and rare earth oxides.

[0011] The rare earth oxide is lanthanum hydroxide.

[0012] By weight, the multi-element metal powder comprises 60-70 parts zinc powder, 30-35 parts zinc-aluminum powder, 1-5 parts magnesium-aluminum powder, and 0.5-1.0 parts rare earth oxides.

[0013] By weight, 1-10 parts of penetration enhancer and 350 parts of dispersant.

[0014] The dispersant includes quartz sand, which can effectively reduce the impact between castings, absorb the heat of reaction, and prevent the castings from sticking together, so that the metal powder and the penetration aid can fully contact on the surface.

[0015] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0016] 1. This invention utilizes the activated boron atoms in the penetration aid, the surface self-cleaning properties of fluoroboric acid, and the reaction mechanism of ammonium chloride to form a zinc penetration layer on the surface of metal components. The reaction rate is fast, the formation effect is good, and the penetration layer is thick and relatively uniform.

[0017] 2. This invention can effectively increase the thickness of the infiltration layer, significantly increase the effective absorption rate of the infiltration agent by 35.40%, and improve the uniformity of the infiltration layer surface by 43%.

[0018] 3. In this invention, potassium fluoroborate mainly plays a catalytic role, and also has a certain purification and exhaust function. The Zn atoms after catalytic activation can easily diffuse into the matrix along the existing vacancies, while the BF3 produced by thermal decomposition can play a purification role on the surface of the casting and impurities. The remaining gases produced by thermal decomposition play a certain exhaust function.

[0019] 4. This invention utilizes the purification mechanism of ammonium chloride. The HCl and NH3 produced by the thermal decomposition of ammonium chloride react with impurities such as iron oxide on the surface of the casting, and the air in the container is discharged to prevent the seepage agent and the workpiece from being oxidized by the air.

[0020] 5. The present invention uses quartz sand dispersant, which can effectively reduce the impact between castings, absorb the heat of reaction, and prevent the castings from sticking together, so that the metal powder and the penetration aid can fully contact on the surface.

[0021] 6. This invention further improves the oxidation and corrosion resistance of metal components, achieving dual innovation in raw materials and processes. Attached Figure Description

[0022] Figure 1 A schematic diagram illustrating the osmosis-enhancing mechanism of ammonium chloride;

[0023] Figure 2 A schematic diagram illustrating the osmosis-enhancing mechanism of ammonium chloride and potassium fluoroborate;

[0024] Figure 3 This is a schematic diagram illustrating the reaction mechanism between iron and the penetration enhancer.

[0025] Figure 4 (a) is the zinc-iron phase diagram, and (b) is a schematic diagram of the zinc-infiltrated layer. Detailed Implementation

[0026] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] The penetration enhancers used in this invention are ammonium chloride and potassium fluoroborate. The specific mechanism is explained below.

[0028] See Figure 1 During the zinc infiltration process using powder embedding on steel as the matrix, the following reaction occurs:

[0029] NH4Cl → NH3 + HCl (1)

[0030] Zn + 2HCl → ZnCl2 + H2 (2)

[0031] ZnCl2 → [Zn] + 2Cl (3)

[0032] When heated, the ammonium chloride in the penetration aid reacts with zinc as follows: First, as shown in (1), at the start of co-permeation, NH4Cl decomposes upon heating; as shown in (2), the generated HCl combines with zinc to form ZnCl2; as shown in (3), the decomposition of ZnCl2 generates active zinc atoms. Since the steel is embedded in zinc powder, the occurrence of the above three reactions results in a higher concentration of active zinc on the surface of the iron matrix than inside, and zinc is deposited on the matrix surface in gaseous form through diffusion. Furthermore, because there are many vacancies on the surface of the iron matrix, active Zn atoms can easily diffuse into the matrix along the existing vacancies.

[0033] Regarding iron, there are the following two reactions:

[0034] 2HCl + Fe → FeCl2 + H2 (4)

[0035] FeCl2 → [Fe] + 2Cl (5)

[0036] Reactions (4) and (5) activate iron, which allows the diffusion of Zn atoms to cause severe lattice distortion in the iron matrix. The presence of lattice distortion accelerates the diffusion of Fe atoms to the outside. The bidirectional diffusion between Zn and Fe atoms leads to the formation of the Fe-Zn phase. The Zn-Fe compounds are classified as ζ phase, δ phase, Γ1 phase and Γ phase from top to bottom according to the thickness of the diffusion layer.

[0037] Besides its catalytic effect, ammonium chloride also plays a certain role in purification and venting during the reaction. The purification effect of ammonium chloride is mainly manifested in the fact that the HCl and NH3 produced by thermal decomposition react with impurities such as iron oxide on the surface of the casting when they come into contact with the iron matrix. This ensures that the contact surface between the casting and the subsequent active metal diffusion agent is thoroughly purified, thereby improving the quality of the resulting co-diffusion layer. The venting effect of ammonium chloride is that after the diffusion aid decomposes into gas upon heating, it expels air from the container, preventing the diffusion agent and the workpiece from being oxidized by the air.

[0038] The osmosis-enhancing mechanism of potassium fluoroborate is as follows: Figure 2 As shown, in the zinc infiltration process using powder embedding on steel as the matrix, the following equation exists:

[0039] KBF4→ KF+BF3 (6)

[0040] KF + HCl → KCl + HF (7)

[0041] Zn + 2HF → ZnF2 + H2 (8)

[0042] ZnF2→[Zn]+2F (9)

[0043] When heated, potassium fluoroborate in the permeation aid reacts with zinc as follows: First, as shown in (6), KBF4 decomposes upon heating at the start of co-permeation; as shown in (7), the generated KF reacts with HCl to generate HF; as shown in (8), the generated HF combines with zinc to generate ZnF2; as shown in (9), the decomposition of ZnF2 generates active zinc atoms. Since the steel is embedded in zinc powder, the occurrence of the above four reactions results in a higher concentration of active zinc on the surface of the iron matrix than inside, and zinc is deposited on the matrix surface in gaseous form through diffusion. Furthermore, since there are many vacancies on the surface of the iron matrix, active Zn atoms can easily diffuse into the matrix along the existing vacancies.

[0044] As for iron, see Figure 3 There were also two reactions:

[0045] 2HF + Fe → FeF₂ + H₂ (10)

[0046] FeF2→[Fe]+2F (11)

[0047] The reactions (10) and (11) activate iron, which allows the diffusion of Zn atoms to cause severe lattice distortion in the iron matrix. The presence of lattice distortion accelerates the diffusion of Fe atoms to the outside. The bidirectional diffusion between Zn and Fe atoms leads to the formation of the Fe-Zn phase. The Zn-Fe compounds are classified as ζ phase, δ phase, Γ1 phase and Γ phase from top to bottom according to the thickness of the diffusion layer.

[0048] Besides its catalytic effect, potassium fluoroborate also plays a role in purification and venting during the reaction. The purification effect is mainly manifested in the BF3 produced by thermal decomposition, which reacts with impurities such as iron oxide on the casting surface upon contact with the iron matrix. This ensures thorough purification of the contact surface between the casting and the subsequent active metal diffusion agent, thereby improving the quality of the resulting co-diffusion layer. The venting effect of potassium fluoroborate involves the decomposition of the diffusion aid into gas upon heating, which removes air from the container, preventing oxidation of the diffusion agent and the workpiece.

[0049] The zinc-iron phase diagram is as follows when a zinc-diffused coating is formed. Figure 4 As shown in (a), the Zn-Fe compounds, in order of penetration layer thickness from top to bottom, are ζ phase, δ phase, Γ1 phase, and Γ phase, and the order of formation of the different phases is as follows: Figure 4 As shown in (b).

[0050] The innovative aspects of this invention will be explained below with reference to embodiments and comparative examples.

[0051] The specific experimental steps are as follows:

[0052] First, the surface of the metal component is degreased, derusted, and cleaned. The amount of multi-element metal powder, dispersant, and infiltration aid to be added is calculated based on the surface area of ​​the metal component. The plate is placed in the co-infiltration furnace, and the metal component is wrapped in the co-infiltration agent. The heating program is started, and the rotation speed and pressure inside the co-infiltration furnace are controlled. The temperature is controlled at 445℃ and maintained for 5 hours. After the co-infiltration process is completed, the metal plate is taken out, cooled to room temperature, and the thickness and uniformity of the infiltration layer are measured.

[0053] It is worth noting that for experimental data where specific conditions are not specified, the experiments should be conducted under standard conditions or as recommended by the manufacturer. For reagents or instruments where the manufacturer is not specified, these can be commercially available products. However, the data obtained from the reaction furnace is based on data from a production furnace in a factory, simulating the actual production environment in a factory workshop.

[0054] Table 1

[0055]

[0056] Table 2

[0057]

[0058] Specific embodiments and comparative data of the present invention are shown in Tables 1 and 2.

[0059] Design thickness calculation formula: Design thickness = Total amount of infiltration agent (zinc-aluminum alloy + aluminum-magnesium alloy + zinc powder + lanthanum hydroxide) / Component surface area * 7.14.

[0060] The anti-fall beam baffles using a penetration enhancer (ammonium fluoroaluminate + ammonium chloride) in Comparative Examples 1-3 had penetration layer thicknesses of 44.56 μm, 43.58 μm, and 44.19 μm, respectively, with a designed thickness of 97.5 μm. The effective absorption rates of the penetration enhancer were 45.70%, 44.70%, and 45.32%, respectively. The average effective absorption rate of the penetration enhancer was 45.24%. The anti-fall beam baffles using a penetration enhancer (potassium fluoroborate + ammonium chloride) in Examples 1-3 had penetration layer thicknesses of 78.33 μm, 79.48 μm, and 78.07 μm, respectively, with a designed thickness of 97.5 μm. The effective absorption rates of the penetration enhancer were 80.34%, 81.52%, and 80.07%, respectively. The average effective absorption rate of the penetration enhancer was 80.64%. Compared with the comparative examples, the effective absorption rate of this invention is significantly improved by 35.40%.

[0061] The cost per furnace for Comparative Examples 1-3 was 276.31 yuan, while the cost per furnace for Examples 1-3 in this invention was 286.40 yuan, an increase of 10.09 yuan, or 3.65%. Despite this 3.65% increase in cost, the effective absorption rate of the penetrant was increased by 35.40%.

[0062] In Comparative Examples 1-3, the co-permeable layer thickness roughness of the anti-falling beam baffles was 13.6%, 19.9%, and 11.1%, respectively, with an average uniformity of 14.86%. In Examples 1-3 of the present invention, the co-permeable layer thickness roughness of the anti-falling beam baffles was 8.3%, 8.2%, and 8.9%, respectively, with an average uniformity of 8.47%. The uniformity of the co-permeable layer of the anti-falling beam baffles of the present invention is significantly improved by 43% compared to the comparative examples.

Claims

1. A co-diffusion agent for corrosion protection of metal components, characterized in that: It includes multi-element powder, dispersant and penetration aid; the multi-element powder includes zinc powder, zinc-aluminum alloy powder, magnesium-aluminum alloy powder and lanthanum hydroxide; by weight, the penetration aid is 8-9 parts potassium fluoroborate and 1-2 parts ammonium chloride.

2. The co-diffusion agent for corrosion protection of metal components as described in claim 1, characterized in that: By weight, the multi-element powder comprises 60-70 parts zinc powder, 30-35 parts zinc-aluminum powder, 1-5 parts magnesium-aluminum powder, and 0.5-1.0 parts lanthanum hydroxide.

3. The co-diffusion agent for corrosion protection of metal components as described in claim 1, characterized in that: The dispersant includes quartz sand.

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