Deep zinc infiltration agent and method for mine support structural member

Abstract

The present application relates to the technical field of material surface treatment, in particular to a deep zinc infiltration agent for mine support structural member and a zinc infiltration method, which comprises the following raw materials: zinc powder, ammonium chloride, sodium chloride, aluminum oxide and complex control type zinc salt composite component. In the present application, in the low temperature stage (<200 DEG C), the organic complexing agent ensures the uniform dispersion of active zinc species on the surface of the carrier, preventing the early agglomeration of zinc chloride; when the temperature continues to rise to the zinc infiltration interval, the organic complexing agent molecules are carbonized in situ, which physically isolates (anchors) the fine zinc chloride / borate particles in the carbon skeleton, preventing them from aggregating into large droplets when melting, thereby maintaining the microdispersibility and effective contact area of the active components of the zinc infiltration agent at high temperature.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment technology, and more specifically, to a deep zinc diffusion agent and zinc diffusion method for mining support structural components. Background Technology

[0002] In harsh industrial environments such as mining, support structural components are subjected to high loads, vibration, impact, and erosion from humid and corrosive media for extended periods, placing extremely high demands on their surface corrosion resistance and wear resistance. Zinc diffusion technology, as a mature and reliable surface strengthening method, forms a zinc-iron alloy layer on the surface of a steel substrate through a thermal diffusion process. This not only provides excellent cathodic protection and good bonding strength but also maintains the original dimensional accuracy of the components, thus it is widely used for the protection of such critical structural components. Chinese patent CN111876723A discloses a zinc diffusion method and corrosion-resistant metal parts. The zinc diffusion method includes: S1, degreasing and derusting the metal parts to be zinc-diffused, and then applying the treated metal... The metal parts and the zinc diffusion agent are placed together in a sealed diffusion tank. The zinc diffusion agent comprises the following components in parts by weight: 20-100 parts of metal powder, 40-80 parts of dispersant, and 0.2-5 parts of decomposing agent, wherein the metal powder includes 60-97 parts of zinc powder and 3-40 parts of magnesium powder. S2, The air in the sealed diffusion tank is expelled, and the valve of the sealed diffusion tank is closed. S3, The sealed diffusion tank is heated to a preset temperature, and then hydrogen gas is introduced and pressurized until the preset hydrogen pressure condition is reached. The temperature is maintained for 1-10 hours, and a diffusion layer is formed on the surface of the metal parts, completing the zinc diffusion process. The zinc diffusion method provided in this application is simple to operate, convenient to use, low in cost, highly economical, and widely applicable.

[0003] The current zinc diffusion technology using zinc chloride as the activating component has shortcomings: although zinc chloride can lower the melting point of the zinc diffusion agent, its dispersibility is limited. Under high temperature conditions, zinc chloride cannot maintain a sufficient diffusion effect. In particular, when the viscosity of the zinc diffusion agent is high, the activation effect of zinc chloride will be limited, thus affecting the diffusion effect. In view of this, we propose a deep zinc diffusion agent and zinc diffusion method for mine support structural components. Summary of the Invention

[0004] The purpose of this invention is to provide a deep zinc diffusion agent and zinc diffusion method for mine support structural components, in order to solve the problem mentioned in the background art that although zinc chloride can lower the melting point of the zinc diffusion agent, its dispersibility is limited. Under high temperature conditions, zinc chloride cannot maintain a sufficient penetration effect. In particular, when the viscosity of the zinc diffusion agent is high, the activation effect of zinc chloride will be limited, thereby affecting the penetration effect.

[0005] This invention provides a deep zinc penetration agent for mine support structural components, comprising the following raw materials: zinc powder, ammonium chloride, sodium chloride, alumina, and a complex-regulated zinc salt composite component.

[0006] The complexation-regulated zinc salt composite component is prepared by reversibly coordinating zinc chloride with an organic complexing agent, introducing inorganic anions, and then mixing and drying.

[0007] Preferably, the zinc powder comprises 30-60 parts by weight, ammonium chloride comprises 5-10 parts by weight, sodium chloride comprises 5-10 parts by weight, alumina comprises 20-30 parts by weight, and complexation-regulated zinc salt composite component comprises 8-15 parts by weight.

[0008] Preferably, the preparation method of the complexation-regulated zinc salt composite component is as follows: an organic complexing agent is added to deionized water and dissolved for 20-40 minutes under stirring conditions of 25-50℃ and 400-600 rpm to obtain an organic complexing agent solution with a mass fraction of 10-20%; under continuous stirring, the temperature is maintained at 40-70℃, zinc chloride is added to the complexing agent solution, and stirring is continued for 30-60 minutes to allow zinc ions to undergo a reversible coordination reaction with the organic complexing agent to form a zinc complex system.

[0009] Add an inorganic anion source of 5-8% of the mass of zinc chloride to the zinc complex system and stir at 50-80℃ for 30-50 min; then dry at 80-110℃ for 6-12 h under nitrogen protection to obtain a complex-regulated zinc salt composite component.

[0010] Preferably, the organic complexing agent is a mixture of tartaric acid and hydroxysuccinic acid, wherein the mass ratio of tartaric acid to hydroxysuccinic acid is 2-4:1.

[0011] Preferably, the molar ratio of zinc chloride to organic complexing agent is 1:0.2-0.6.

[0012] Preferably, the inorganic anion source is composed of a mixture of boric acid and sodium metaborate, wherein the mass ratio of boric acid to sodium metaborate is 1-3:1.

[0013] As a preferred embodiment, the preparation method of the deep zinc infiltration agent for the mining support structure is as follows: zinc powder and alumina are added to a mixing device and mechanically mixed at room temperature for 15-30 minutes to obtain a zinc powder-carrier premix; ammonium chloride and sodium chloride are added to the zinc powder-carrier premix and mixed at room temperature for 10-20 minutes, followed by the addition of a complex-regulated zinc salt composite component and further mixing for 20-40 minutes to obtain a mixture; the mixture is dried at 80-120℃ for 4-8 hours and cooled to obtain the deep zinc infiltration agent for the mining support structure.

[0014] On the other hand, the present invention provides a zinc diffusion method for a deep zinc diffusion agent for mine support structures. The method using the above-mentioned deep zinc diffusion agent for mine support structures includes the following steps: S1.1, degreasing, derusting and drying the mine support structure to obtain a pretreated mine support structure.

[0015] S1.2 The prepared deep zinc diffusion agent and the pretreated mine support structure are placed together in a tube furnace. Under the protective atmosphere of nitrogen with a continuous flow rate of 1.5 L / min, the temperature is raised to the zinc diffusion temperature for diffusion zinc diffusion. After the temperature is maintained, the furnace is cooled to obtain the zinc-dipped mine support structure.

[0016] Preferably, in step S1.1, the degreasing process is as follows: the mining support structure is placed in a sodium hydroxide solution with a mass fraction of 3-8% and immersed at 40-70°C for 10-20 minutes. After removal, it is rinsed with clean water until there is no oil residue on the surface.

[0017] The rust removal process is as follows: Place the degreased mining support structure in a 5-10% hydrochloric acid solution and pickle it at 20-40℃ for 10-30 minutes. After removing it, rinse it thoroughly with clean water, neutralize it with a 0.5-2.0% sodium carbonate solution, and then rinse it again with clean water.

[0018] The drying process involves placing the rust-removed mine support structure in a hot air environment at 80-120℃ for 50-90 minutes.

[0019] Preferably, in step S1.2, the zinc diffusion temperature is 420-520℃ and the zinc diffusion time is 3-6h.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: In the deep zinc diffusion agent and zinc diffusion method for mine support structural components of the present invention, at the low temperature stage (<200℃), the organic complexing agent ensures the uniform dispersion of active zinc species on the carrier surface and prevents early agglomeration of zinc chloride; when the temperature continues to rise to the zinc diffusion range, the organic complexing agent molecules are carbonized in situ, physically isolating (anchoring) the fine zinc chloride / borate particles in the carbon skeleton, preventing them from agglomerating into large droplets during melting, thereby maintaining the microscopic dispersion and effective contact area of ​​the active components of the zinc diffusion agent at high temperature; the introduced boric acid and sodium metaborate can form a low-melting-point borate glass melt at the high temperature of zinc diffusion, which can dissolve the high-melting-point, dense zinc oxide (ZnO) or basic zinc salt solid film generated by the reaction of zinc chloride with trace amounts of oxygen and water during conventional zinc diffusion process, thereby maintaining the continuous activation of the metal surface.

[0021] Although the system has a high salt content, the introduced borate and alumina carrier form a high-viscosity boroaluminate glass phase at high temperature. This high-viscosity liquid film coats the surface of zinc powder particles, which not only prevents excessive agglomeration and loss of zinc powder, but also avoids the overall sintering of the penetrant, thus acting as a liquid phase spacer. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a deep zinc penetration agent for mine support structural components, comprising the following raw materials: zinc powder, ammonium chloride, sodium chloride, alumina, and a complex-regulated zinc salt composite component.

[0024] The complexation-regulated zinc salt composite component is prepared by reversibly coordinating zinc chloride with an organic complexing agent, introducing inorganic anions, and then mixing and drying.

[0025] Ammonium chloride (CAS No.: 12125-02-9) was purchased from Shanxi Wencheng Chemical Co., Ltd.

[0026] Sodium chloride (CAS No.: 7647-14-5) was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0027] Alumina (CAS No.: 1344-28-1) was purchased from Hubei Huifu Nanomaterials Co., Ltd.

[0028] Zinc chloride (CAS No.: 7646-85-7) was purchased from Lanzhou Hongsheng Fine Chemical Co., Ltd.

[0029] Tartaric acid (CAS No.: 526-83-0) was purchased from Shanghai Haoyuan Biomedical Technology Co., Ltd.

[0030] Hydroxysuccinic acid (CAS No.: 617-48-1) was purchased from Shenzhen Lefu Biotechnology Co., Ltd.

[0031] Boric acid (CAS No.: 10043-35-3) was purchased from Changzhou Guxu Chemical Co., Ltd.

[0032] Sodium metaborate (CAS No.: 7775-19-1) was purchased from Hubei Chengfeng Chemical Co., Ltd.

[0033] Example 1: A zinc diffusion method for a deep zinc diffusion agent for a mine support structure, comprising the following steps: S1.1, placing the mine support structure in a 3% sodium hydroxide solution and immersing it at 40°C for 10 minutes, then rinsing it with clean water until there is no oil residue on the surface.

[0034] After degreasing, the mine support structure is placed in a 5% hydrochloric acid solution and pickled at 20°C for 10 minutes. After removal, it is thoroughly rinsed with water, neutralized with a 0.5% sodium carbonate solution, and then rinsed again with water.

[0035] The rust-removed mine support structure was dried in a hot air environment at 80℃ for 90 minutes to obtain the pretreated mine support structure.

[0036] S1.2 The prepared deep zinc diffusion agent and the pretreated mine support structure are placed together in a tube furnace. Under the protective atmosphere of nitrogen with a continuous flow rate of 1.5 L / min, the temperature is raised to the zinc diffusion temperature of 420℃ for diffusion zinc diffusion. The zinc diffusion time is 3 h. After the heat preservation is completed, the furnace is cooled to obtain the zinc-treated mine support structure.

[0037] The preparation method of the complex-regulated zinc salt composite component is as follows: An organic complexing agent (made by mixing tartaric acid and hydroxysuccinic acid in a mass ratio of 2:1) is added to deionized water and dissolved for 20 min under stirring at 25℃ and 400 rpm to obtain an organic complexing agent solution with a mass fraction of 10%; under continuous stirring and maintaining the temperature at 40℃, zinc chloride is added to the complexing agent solution (the molar ratio of zinc chloride to organic complexing agent is 1:0.4), and stirring is continued for 30 min to allow zinc ions to undergo a reversible coordination reaction with the organic complexing agent to form a zinc complex system.

[0038] An inorganic anion source (composed of boric acid and sodium metaborate in a mass ratio of 1:1) was added to the zinc complexing system at 7% of the mass of zinc chloride, and the mixture was stirred at 50°C for 30 min. Then, under nitrogen protection, the mixture was dried at 80°C for 6 h to obtain a complexation-regulated zinc salt composite component.

[0039] The preparation method of deep zinc infiltration agent for mine support structural components is as follows: 30 parts by weight of zinc powder and 20 parts by weight of alumina are added to a mixing device and mechanically mixed at room temperature for 15 minutes to obtain a zinc powder-carrier premix; 5 parts by weight of ammonium chloride and 5 parts by weight of sodium chloride are added to the zinc powder-carrier premix, and the mixture is continued to be mixed at room temperature for 10 minutes, followed by the addition of 8 parts by weight of complex-regulated zinc salt composite component, and the mixture is continued to be mixed for 20 minutes to obtain a mixture; the mixture is dried at 80℃ for 8 hours, and after cooling, a deep zinc infiltration agent for mine support structural components is obtained.

[0040] Example 2: The difference between this example and Example 1 is that the molar ratio of zinc chloride to organic complexing agent is 1:0.2.

[0041] Example 3: The difference between this example and Example 1 is that the molar ratio of zinc chloride to organic complexing agent is 1:0.6.

[0042] Example 4: The difference between this example and Example 1 is that the inorganic anion source accounts for 5% of the mass of zinc chloride.

[0043] Example 5: The difference between this example and Example 1 is that the inorganic anion source accounts for 8% of the mass of zinc chloride.

[0044] Determination steps for zinc release onset temperature and main release temperature range: Accurately weigh approximately 10-20 mg of the prepared composite component powder sample and place it in an alumina crucible specifically designed for the TG-DSC instrument; ensure the sample is spread evenly and without accumulation; place the crucible containing the sample into the instrument's sample cell, and use an empty crucible as a reference; set a dynamic nitrogen (N2) atmosphere, typically at a flow rate of 50 mL / min; program the temperature from room temperature (e.g., 30°C) to 600°C at a constant rate of 10°C / min (this temperature must cover and exceed the upper limit of the zinc diffusion temperature of 520°C); start the test, and the instrument simultaneously records the mass change curve (TG curve) and heat flow change curve (DSC curve) of the sample during the heating process; Zinc release onset temperature: Observe the TG curve, and draw a tangent line from the first identifiable inflection point or deviation from the smooth baseline to determine the corresponding temperature point, which is the onset temperature; Main release temperature range: Observe the segment on the TG curve where the mass decreases most rapidly and significantly, typically taking the temperature range between the inflection points of this segment or on both sides of the peak weight loss rate.

[0045] From the complete TG data obtained from the above tests, the residual rate at 520℃ was determined: the remaining mass (m) of the sample at 520℃ was read from the TG data. end ) and initial mass (m0); the calculation formula is: 520℃ residual rate (%) = (m end / m0)×100%. Among them, the higher the residual rate, the more complete the skeleton structure formed after the organic complexing agent is carbonized is retained, and no excessive decomposition or volatilization has occurred, which is beneficial to the physical isolation effect at high temperature.

[0046] Procedure for determining the specific surface area retention rate after aging at 400℃ for 24 hours: Take a small amount of the prepared component powder and determine its initial specific surface area (S0) using a specific surface area and porosity analyzer (such as the BET method). Weigh a sufficient amount of the same batch of samples and place them in a high-temperature resistant crucible. Under a nitrogen atmosphere, place the crucible in a muffle furnace and program the temperature to 400℃ and maintain it at a constant temperature for 24 hours to simulate the long-term thermal environment of the zinc diffusion agent. After cooling, measure the specific surface area (S0) of the aged samples again.t The calculation formula is: Specific surface area retention rate (%) = (S) t / S0)×100%.

[0047] Table 1 Performance data of complex-regulated zinc salt composites

[0048] As shown in Table 1, the test data from Examples 1 to 5 show that the organic complexing agent can ensure the uniform dispersion of active zinc species on the carrier surface and prevent early aggregation of zinc chloride. When the temperature continues to rise to the zinc diffusion range, the organic complexing agent molecules carbonize in situ, physically isolating (anchoring) the fine zinc chloride / borate particles in the carbon skeleton, preventing them from agglomerating into large droplets during melting. This maintains the micro-dispersion and effective contact area of ​​the active components of the zinc diffusion agent at high temperatures. Moreover, since the organic complexing agent can form a carbon skeleton, the residual rate at 520°C in the test data of the above examples is relatively high, which can maintain the release at high temperatures.

[0049] As the proportion of organic complexing agent increased (from 1:0.2 in Example 2 to 1:0.6 in Example 3), the onset temperature and main range of zinc release shifted to higher temperatures, and the residual rate at 520°C increased significantly. This is because an appropriate amount of organic complexing agent is converted in situ into a stable porous carbon framework at high temperatures. This framework not only locks in the inorganic salt components, reducing ineffective volatilization, but also acts as a physical barrier to prevent component aggregation. The low residual rate (41.9%) in Example 2 indicates that a low proportion of complexing agent cannot form a sufficient carbon framework, leading to premature decomposition and volatilization of the active components, making it difficult to maintain continuous release at high temperatures.

[0050] As shown in Table 1, Examples 3 and 5 exhibited the highest specific surface area retention rates. This indicates that the carbon skeleton formed by sufficient organic complexing agents and the isolation effect of inorganic borates can effectively inhibit the sintering and agglomeration of active components at high temperatures, maintaining their porous and loose microstructure, thereby ensuring the durability of the active surface and the unobstructed mass transfer channels during zinc diffusion. Conversely, as in Examples 2 and 4, due to insufficient components, the specific surface area decreased significantly after high-temperature aging, indicating severe agglomeration of active components, which will lead to a reduction in the effective reaction area and uneven diffusion during zinc diffusion.

[0051] As shown in Table 1, adding an inorganic anion source causes the release temperature range to shift slightly towards higher temperatures (Example 5 compared to Example 1), because the introduced anions participate in the stability of the local structure.

[0052] Tartaric acid and hydroxysuccinic acid are both polyhydroxy and polycarboxyl organic acids. The simultaneous presence of carboxyl and hydroxyl coordination sites in their molecules allows them to form multi-site coordination and bridging organic-inorganic composite structures when coexisting with zinc ions and boron-oxygen anions generated by the hydrolysis of inorganic anion sources. Compared with single organic acid or simple zinc salt systems, the coordination and interaction between organic and inorganic components in this composite structure restricts the free movement of organic molecules or coordination units to a certain extent, causing a significant change in the thermal decomposition behavior of the system. Therefore, the main weight loss range (320-480℃) observed in thermogravimetric analysis does not correspond to the decomposition of simple organic acids.

[0053] Example 6: A zinc diffusion method for a deep zinc diffusion agent for a mine support structure, comprising the following steps: S1.1, placing the mine support structure in a 5% sodium hydroxide solution by mass, immersing it at 60°C for 15 minutes, and then rinsing it with clean water until there is no oil residue on the surface.

[0054] After degreasing, the mine support structure was placed in an 8% hydrochloric acid solution and pickled at 30°C for 20 minutes. After removal, it was thoroughly rinsed with water and neutralized with a 1.0% sodium carbonate solution. Then it was rinsed again with water.

[0055] The rust-removed mine support structure was dried in a hot air environment at 100℃ for 60 minutes to obtain the pretreated mine support structure.

[0056] S1.2 The prepared deep zinc diffusion agent and the pretreated mine support structure are placed together in a tube furnace. Under the protective atmosphere of nitrogen with a continuous flow rate of 1.5 L / min, the temperature is raised to the zinc diffusion temperature of 450℃ for diffusion zinc diffusion. The zinc diffusion time is 4 h. After the heat preservation is completed, the furnace is cooled to obtain the zinc-treated mine support structure.

[0057] The preparation method of the complex-regulated zinc salt composite component is as follows: An organic complexing agent (made by mixing tartaric acid and hydroxysuccinic acid in a mass ratio of 3:1) is added to deionized water and dissolved for 30 min under stirring at 40℃ and 500 rpm to obtain an organic complexing agent solution with a mass fraction of 15%; under continuous stirring and maintaining the temperature at 60℃, zinc chloride is added to the complexing agent solution (the molar ratio of zinc chloride to organic complexing agent is 1:0.4), and stirring is continued for 45 min to allow zinc ions to undergo a reversible coordination reaction with the organic complexing agent to form a zinc complex system.

[0058] An inorganic anion source (composed of boric acid and sodium metaborate in a mass ratio of 2:1) was added to the zinc complex system at 7% of the mass of zinc chloride, and the mixture was stirred at 65°C for 40 min. Then, under nitrogen protection, the mixture was dried at 90°C for 10 h to obtain a complex-regulated zinc salt composite component.

[0059] The preparation method of deep zinc infiltration agent for mine support structural components is as follows: 45 parts by weight of zinc powder and 25 parts by weight of alumina are added to a mixing device and mechanically mixed at room temperature for 20 minutes to obtain a zinc powder-carrier premix; 8 parts by weight of ammonium chloride and 8 parts by weight of sodium chloride are added to the zinc powder-carrier premix, and the mixture is continued to be mixed at room temperature for 15 minutes, followed by the addition of 12 parts by weight of complex-regulated zinc salt composite component, and the mixture is continued to be mixed for 30 minutes to obtain a mixture; the mixture is dried at 100℃ for 6 hours, and after cooling, a deep zinc infiltration agent for mine support structural components is obtained.

[0060] Example 7: The difference between this example and Example 6 is that 8 parts by weight of complex-regulated zinc salt composite component are used.

[0061] Example 8: The difference between this example and Example 6 is that 15 parts by weight of complex-regulated zinc salt composite component are used.

[0062] Example 9: The difference between this example and Example 6 is that the zinc diffusion temperature is 420°C.

[0063] Example 10: The difference between this example and Example 6 is that the zinc diffusion temperature is 520°C.

[0064] Steps for determining the thickness of the diffusion layer: On the zinc-diffused mining support structure, select representative locations (such as planes and edges) and cut samples perpendicular to the diffusion layer surface using methods such as wire cutting; to prevent the sample edges from being chamfered or chipped in subsequent processing, use resin for cold mounting; then grind the cross-section step by step with wet sandpaper from coarse to fine (e.g., 400# to 2000#) until there are no obvious scratches; use diamond polishing paste on a polishing machine for mirror polishing; wipe the cross-section for several seconds with a specific etching agent (2-4% nitric acid alcohol solution) to clearly show the boundary between the diffusion layer and the substrate; place the treated sample under a metallographic microscope, and use an eyepiece micrometer to measure the vertical distance from the surface to the substrate (the part not affected by diffusion) at at least 5 evenly distributed locations (avoiding defects such as holes and impurities), this is the total diffusion layer thickness.

[0065] The main phase composition determination steps are as follows: Gently scrape a small amount of diffusion layer powder from the workpiece surface; grind the powder until it is smooth to the touch (usually requiring a particle size of <360 mesh or about 40 micrometers) to eliminate orientation effects; uniformly fill the powder into the groove of the special sample holder, and gently press it with a flat glass plate to form a flat and dense test plane; then install the sample holder on the XRD sample stage, ensuring that the surface is flat and centered; set the scanning parameters, usually the starting angle (2θ) is 20°, the ending angle is 80°, and the scanning speed is set according to the accuracy requirements (e.g., 2° / minute); start the test, and compare the diffraction peak position (2θ angle) and relative intensity of the test spectrum with the standard cards of Fe-Zn phases in the PDF card library of the Joint Powder Diffraction Standards Committee to determine the main phases present in the diffusion layer.

[0066] The strength testing procedure is as follows: The hammer impact method is used (referencing standard JB / T 5067 "Powder Zinc Infiltration"): Select the zinc-infiltrated sample and fix it on a bench vise; use a 0.25kg test hammer to strike the sample surface. During striking, the hammer head should fall freely, perpendicular to the sample surface; strike once at three locations at least 6mm apart. Rating criteria: Pass (no protrusions, cracks, or peeling of the zinc infiltration layer at the striking point, only hammer marks remaining); Fail (cracks, blocky peeling, or exposure of the substrate appear in the zinc infiltration layer at the striking point).

[0067] Procedure for determining the time to red rust formation in a neutral salt spray test: Cut a sample of the specified size from the zinc-plated part, or use a small sample from the same batch; clean the surface oil with a non-corrosive solvent (such as acetone), but do not damage the zinc plating layer; place the sample in the salt spray chamber at a 15°-30° angle to the vertical direction, maintaining distance between samples and between the samples and the chamber walls to ensure that the salt spray can freely settle on all surfaces; Test conditions: (5±1)% sodium chloride solution, pH adjusted to 6.5-7.2 (at 35℃), chamber temperature: (35±2)℃, salt spray deposition rate: 1-2 mL / h per 80 cm² collection area; start the test and begin continuous spraying; according to the corrosion resistance prediction, periodically interrupt the test (e.g., every 24, 48, 96, 240 hours, etc.) and take out the sample for inspection; during inspection, gently rinse the surface salt with running water at ≤40℃ and then blow dry; observe the sample surface under a magnifying glass; the red rust time is defined as the cumulative test time corresponding to the first appearance of red rust (not white corrosion products of zinc layer) of the base steel corrosion products on the sample surface.

[0068] Table 2 Performance data of zinc-diluent coating

[0069] As shown in Table 2, from Example 7 (8 parts) to Example 8 (15 parts), the thickness of the diffusion layer increased and the proportion of the δ phase significantly increased. At a lower addition amount (Example 7), the role of the composite component was to disperse and activate in the early stage. The zinc diffusion process still retained more traditional gas phase transport characteristics, resulting in a faster zinc atom deposition rate on the workpiece surface, which easily formed a zinc-rich ζ phase surface layer. Although this phase layer had a certain thickness, it would partially hinder the subsequent internal diffusion of zinc atoms. When the addition amount was increased to Example 8, sufficient borate and other components could form a more continuous and stable viscous melt film at the zinc diffusion interface. It slowed down the transport rate of active zinc species from the diffusion agent to the workpiece surface. Its effect was to inhibit the excessive growth of the surface ζ phase and maintain the interfacial zinc potential in a moderate range that was more conducive to the nucleation and growth of the δ phase. At the same time, the continuous supply of zinc atoms allowed for more sufficient bulk diffusion into the iron matrix during a longer holding time, thereby forming a thicker diffusion layer dominated by the δ phase.

[0070] As shown in Table 2, increasing the temperature significantly increases the thickness of the infiltration layer (Examples 9, 6, and 10), and at the same time drives the phase structure to transform towards a higher iron content (ζ phase to δ phase); however, excessively high temperatures (Example 10, 520°C) will lead to coarse grains and increased porosity, which will make the structure loose and impair its compactness.

[0071] A suitable temperature (such as 450°C in Example 6) can produce a dense δ phase layer that is well bonded to the matrix; if the temperature is too low (Example 9, 420°C), diffusion is insufficient and the bonding force is poor; if the temperature is too high (Example 10), although the layer is thick, the structure is loose and the bonding force decreases. Moreover, the loose structure will accelerate the penetration of corrosive media, resulting in the increase in corrosion resistance being lower than the increase in thickness. Among them, Example 9 serves as a low-temperature comparative example outside the scope to demonstrate the effect of excessively low temperature.

[0072] As shown in Table 2, the bonding strength of all examples (Examples 6-10) was qualified after hammer impact test, with only hammer marks left on the surface and no coating peeling or cracking. This indicates that the deep zinc diffusion agent provided by the present invention can promote the full interdiffusion reaction between zinc atoms and iron matrix within a wide range of component addition (8-15 parts) and temperature range (420-520℃), forming a strong metallurgical bonding interface.

[0073] Based on the above measurements, Example 6 achieved the best balance between thickness, dense phase (δ phase) formation, bonding strength and corrosion resistance. Therefore, Example 6 is selected as the optimal example.

[0074] Comparative Example 1: The difference between this example and Example 6 is that no complexation-regulated zinc salt composite component was added.

[0075] Comparative Example 2: The difference between this example and Example 6 is that zinc chloride is used instead of the complex-regulated zinc salt composite component.

[0076] Comparative Example 3: The difference between this example and Example 6 is that the organic complexing agent is replaced with disodium ethylenediaminetetraacetate.

[0077] Table 3 Performance data of zinc-diluent coating

[0078] Compared with Example 6, Comparative Example 1 showed a comprehensive deterioration in all indicators; the infiltration layer was the thinnest, the corrosion resistance time was the shortest, and the bonding strength was poor.

[0079] In this comparative example, the zinc supply relies entirely on the contact and diffusion of solid zinc powder, resulting in low activity and poor mass transfer efficiency. Lacking the gas-phase transport activation effect provided by composite components, zinc atoms have difficulty penetrating deep into the matrix, leading to a thin diffusion layer dominated by a loose ζ phase. This porous structure has weak bonding force, making it extremely easy for corrosive media to penetrate, thus resulting in extremely poor corrosion resistance.

[0080] Comparative Example 2 performed better than Comparative Example 1 but worse than Example 6, placing it at an intermediate level. Ordinary zinc chloride can decompose to produce active gas when heated, which has a certain activating effect, thus its performance is better than the traditional process without additives. However, its release is intense and uncontrollable, and it is consumed quickly in the early stage, making it unable to provide a stable zinc potential during the zinc infiltration process that lasts for several hours. More importantly, zinc chloride is extremely prone to crystallization during cooling and storage, leading to agglomeration of the infiltration agent and uneven composition, which is reflected in the mixed and uneven structure of the infiltration layer.

[0081] Compared with Example 6, Comparative Example 3 showed severe performance failure and was almost unable to form an effective infiltration layer.

[0082] Disodium ethylenediaminetetraacetate (EDTA) has high thermal stability, and its decomposition products contain a large amount of nitrogen. During zinc diffusion, nitrogen-containing products can easily cause brittle nitriding of the diffusion layer, reducing the bonding force. At the same time, the dense tar-like residue produced by EDTA decomposition will coat the surface of zinc powder, hindering diffusion (decomposition in high temperature and oxygen-deficient environment tends to form dense, non-porous tar-like residue, which covers the zinc powder and workpiece surface, blocking the gas phase transport channels of zinc atoms).

[0083] 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 preferred examples and are not intended to limit 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 the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep zinc infiltration agent for mining support structural components, characterized in that, It includes the following raw materials: zinc powder, ammonium chloride, sodium chloride, alumina, and complex-regulated zinc salt composite components; The complexation-regulated zinc salt composite component is prepared by reversibly coordinating zinc chloride with an organic complexing agent, introducing inorganic anions, and then mixing and drying.

2. The deep zinc diffusion agent for mine support structural components according to claim 1, characterized in that, The composition includes 30-60 parts by weight of zinc powder, 5-10 parts by weight of ammonium chloride, 5-10 parts by weight of sodium chloride, 20-30 parts by weight of alumina, and 8-15 parts by weight of complex-regulated zinc salt composite component.

3. The deep zinc diffusion agent for mine support structural components according to claim 2, characterized in that, The preparation method of the complex-regulated zinc salt composite component is as follows: The organic complexing agent is added to deionized water and dissolved for 20-40 minutes under stirring at 25-50℃ and 400-600 rpm to obtain an organic complexing agent solution with a mass fraction of 10-20%. Under continuous stirring and while maintaining the temperature at 40-70℃, zinc chloride is added to the complexing agent solution and stirring is continued for 30-60 minutes to allow zinc ions to undergo a reversible coordination reaction with the organic complexing agent, forming a zinc complex system. Add an inorganic anion source of 5-8% of the mass of zinc chloride to the zinc complex system and stir at 50-80℃ for 30-50 min; then dry at 80-110℃ for 6-12 h under nitrogen protection to obtain a complex-regulated zinc salt composite component.

4. The deep zinc diffusion agent for mine support structural components according to claim 3, characterized in that, The organic complexing agent is a mixture of tartaric acid and hydroxysuccinic acid, wherein the mass ratio of tartaric acid to hydroxysuccinic acid is 2-4:

1.

5. The deep zinc diffusion agent for mine support structural components according to claim 3, characterized in that, The molar ratio of zinc chloride to the organic complexing agent is 1:0.2-0.

6.

6. The deep zinc diffusion agent for mine support structural components according to claim 3, characterized in that, The inorganic anion source is composed of a mixture of boric acid and sodium metaborate, wherein the mass ratio of boric acid to sodium metaborate is 1-3:

1.

7. The deep zinc diffusion agent for mine support structural components according to claim 2, characterized in that, The preparation method of the deep zinc diffusion agent for the mining support structural components is as follows: Zinc powder and alumina are added to a mixing device and mechanically mixed at room temperature for 15-30 minutes to obtain a zinc powder-carrier premix. Ammonium chloride and sodium chloride are added to the zinc powder-carrier premix and mixed at room temperature for 10-20 minutes. Then, a complex-regulated zinc salt composite component is added and mixed for 20-40 minutes to obtain a mixture. The mixture is dried at 80-120℃ for 4-8 hours and cooled to obtain a deep zinc infiltration agent for mine support structures.

8. A zinc diffusion method for a deep zinc diffusion agent for mine support structural components, using the deep zinc diffusion agent for mine support structural components as described in any one of claims 1-7, characterized in that, The zinc diffusion method is as follows: S1.1 The mine support structure is degreased, derusted and dried to obtain pretreated mine support structure; S1.2 The prepared deep zinc diffusion agent and the pretreated mine support structure are placed together in a tube furnace. Under the protective atmosphere of nitrogen with a continuous flow rate of 1.5 L / min, the temperature is raised to the zinc diffusion temperature for diffusion zinc diffusion. After the temperature is maintained, the furnace is cooled to obtain the zinc-dipped mine support structure.

9. The zinc diffusion method for deep zinc diffusion agent used in mine support structural components according to claim 8, characterized in that, In S1.1, the degreasing treatment step is as follows: the mining support structure is placed in a sodium hydroxide solution with a mass fraction of 3-8% and immersed at 40-70℃ for 10-20 minutes. After removal, it is rinsed with clean water until there is no oil residue on the surface. The rust removal process is as follows: Place the degreased mining support structure in a 5-10% hydrochloric acid solution and pickle it at 20-40℃ for 10-30 minutes. After removing it, rinse it thoroughly with clean water, neutralize it with a 0.5-2.0% sodium carbonate solution, and then rinse it again with clean water. The drying process involves placing the rust-removed mine support structure in a hot air environment at 80-120℃ for 50-90 minutes.

10. The zinc diffusion method for deep zinc diffusion agent used in mine support structural components according to claim 8, characterized in that, In S1.2, the zinc diffusion temperature is 420-520℃, and the zinc diffusion time is 3-6h.

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