A grouting composite corrosion inhibitor for deep coal mine support anchor cable and a preparation method and application thereof

Abstract

The present application relates to the technical field of corrosion inhibitor additives, and particularly relates to a composite corrosion inhibitor for deep coal mine support anchor cable, a preparation method and application thereof.A grouting composite corrosion inhibitor for deep coal mine support anchor cable, the composite corrosion inhibitor is composed of surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO.Cr2O3 can form a dense oxide film on the surface of the anchor cable, effectively isolating the corrosion of corrosive media; the adsorption-deposition dual action of Na3PO4 can generate a protective phosphate film on the metal surface, further inhibiting corrosion; the cathodic protection and physical barrier effect of nano ZnO slow down the electrochemical corrosion rate of the anchor cable. The synergistic effect of structural reinforcement and electrochemical coupling of the three components makes the corrosion inhibitor exhibit excellent corrosion resistance in the deep coal mine environment. The composite corrosion inhibitor is applied to the deep mine anchoring grouting material, providing a new solution for deep coal resource development, and effectively expanding the diversity of functional products.

Description

Technical Field

[0001] This invention relates to the field of corrosion inhibitors, and in particular to a composite corrosion inhibitor for deep coal mine support anchor cables, its preparation method, and its application. Background Technology

[0002] The engineering geological environment of deep coal mines exhibits typical characteristics of "three highs and one disturbance," namely, the combined effects of high ground stress, high osmotic pressure, and high temperature, and strong mining disturbance. The deformation control of the surrounding rock in roadways is highly dependent on the prestressed anchor cable support system. As a key component of roadway support in deep coal mines, the corrosion of anchor cables not only reduces the overall strength of the support structure but can also lead to major safety accidents such as roadway collapse. The complexity and harshness of the deep coal mining environment place extremely high demands on the durability and safety of the support structure. Deep coal mine environments are characterized by high ground stress, high humidity, and multiple corrosive media, all of which accelerate the corrosion process of anchor cables. High ground stress causes anchor cables to bear greater mechanical loads, easily leading to stress corrosion cracking; high humidity provides conditions for electrochemical corrosion, with groundwater, condensate, and other media contacting the anchor cable surface to form corrosion cells; furthermore, deep coal mine environments often contain acidic gases such as H2S and CO2, as well as Cl... - SO4 2- Corrosive ions and other media can react chemically with anchor cable metal, leading to localized corrosion, pitting, and stress corrosion cracking. With increasing coal mining depth, the high ground stress, high humidity, and highly corrosive media (such as groundwater and acidic gases) in the surrounding rock of roadways make the corrosion problem of support materials increasingly prominent.

[0003] Existing anchor cable corrosion protection technologies, such as surface coatings, cathodic protection, and traditional corrosion inhibitor additions, all have limitations in practical applications. While surface coatings (such as epoxy resin coatings and zinc-aluminum alloy coatings) can isolate corrosive media to some extent, they are prone to peeling under high ground stress and mechanical wear, making long-term effective protection difficult. Cathodic protection protects anchor cables through impressed current or sacrificial anodes, but in deep coal mine environments, due to the complex geological conditions, the installation and maintenance costs of cathodic protection systems are high, and their effectiveness is limited. Traditional corrosion inhibitors (such as molybdates and silicates) have limited corrosion inhibition effects in deep coal mine environments and may adversely affect the strength of grouting materials. Therefore, developing an anchor cable grouting corrosion inhibitor suitable for deep coal mine environments has become an important direction in current coal mine support technology research.

[0004] In recent years, composite corrosion inhibitors have attracted widespread attention in the field of metal corrosion protection due to their synergistic effect and multifunctionality. Composite corrosion inhibitors are usually composed of two or more corrosion-inhibiting components, and the synergistic effect of different components can significantly improve the corrosion inhibition effect. However, existing research focuses on the performance of corrosion inhibitors in single environments, and research on composite corrosion inhibitors for the complex environments of deep coal mines (such as high ground stress, high humidity, and multiple corrosive media) is still relatively lacking. Summary of the Invention

[0005] One objective of this invention is to provide a grouting composite corrosion inhibitor for anchor cables used in deep coal mines. This composite corrosion inhibitor has high corrosion inhibition efficiency and protective performance in deep coal mine mining environments, and is highly applicable and targeted.

[0006] The technical solution of the grouting composite corrosion inhibitor for deep coal mine support anchor cables provided by the present invention is as follows: A composite corrosion inhibitor for grouting anchor cables used in deep coal mines, the composite corrosion inhibitor being composed of surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO.

[0007] Preferably, the mass ratio of the surface-modified nano-Cr2O3, Na3PO4 and surface-modified nano-ZnO is 5:1 to 10:1 to 10.

[0008] This invention provides a highly efficient, environmentally friendly, and industrially scalable corrosion protection solution for deep coal mine anchor cable grouting systems, with broad application prospects. Specifically, the passivation film mechanism of Cr2O3 forms a dense oxide film on the anchor cable surface, effectively isolating it from corrosive media; the adsorption-precipitation dual effect of Na3PO4 allows it to chemically react with the metal surface to generate a protective phosphate film, further inhibiting corrosion; and the cathodic protection and physical barrier effect of nano-ZnO slows down the electrochemical corrosion rate of the anchor cable. Through a synergistic enhancement mechanism of spatial complementarity, structural reinforcement, and electrochemical coupling, these three components enable this corrosion inhibitor to exhibit excellent corrosion resistance in deep coal mine environments.

[0009] The second objective of this invention is to provide a method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables. This preparation method enhances interfacial compatibility and avoids local concentration differences through nano-sizing (ball milling), surface modification (silane coupling agent treatment), and ultrasonic dispersion, thereby enabling the composite corrosion inhibitor to function better.

[0010] The technical solution of the present invention for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables is as follows: A method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables includes the following steps: S1. Nano-sizing treatment: Cr2O3 and ZnO powders are ball-milled under inert gas protection to obtain nano-Cr2O3 and nano-ZnO. S2. Surface modification treatment: Nano Cr2O3 and nano ZnO are dispersed in an organic solution containing a silane coupling agent, ultrasonically treated, and then dried to obtain surface-modified nano Cr2O3 and surface-modified nano ZnO. S3. Preparation of composite corrosion inhibitor: A composite corrosion inhibitor is prepared by mixing surface-modified nano-Cr2O3 and surface-modified nano-ZnO with Na3PO4.

[0011] Preferably, in step S1, Cr2O3 and ZnO powders are placed in a ball mill, with zirconia balls as the medium and a ball-to-material ratio of 10:1, and ball milled at 300 rpm for 4 hours under inert gas protection to obtain nano-Cr2O3 and nano-ZnO with a particle size ≤200 nm.

[0012] Preferably, in step S2, nano-Cr2O3 and nano-ZnO are dispersed in an ethanol solution containing 1 wt.% silane coupling agent, ultrasonically treated for 30 min, and then dried at 60°C to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO.

[0013] This invention involves nano-sizing and surface modification of chromium oxide (Cr2O3) and zinc oxide (ZnO) powders. A high-energy ball mill is used under nitrogen protection, with strict control of the ball-to-powder ratio, rotation speed, and milling time. Combined with intermittent operation, nanoparticles with a particle size ≤200nm are obtained. These nanoparticles are then ultrasonically dispersed in an ethanol solution containing a silane coupling agent, vacuum dried, and characterized to confirm successful surface modification.

[0014] The third objective of this invention is to provide an application of a composite corrosion inhibitor for grouting anchor cables in deep coal mines. This composite corrosion inhibitor is designed to meet the corrosion protection needs of anchoring grouting materials in deep mines, filling the technological gap in corrosion inhibitors specifically for high-mineralization underground engineering environments. It provides a novel protective solution for deep coal resource development and effectively expands the diversity of functional products. This composite corrosion inhibitor is not only suitable for deep coal mine roadway support but can also be extended to other highly corrosive environments, such as tunnel engineering, underground engineering, and marine engineering.

[0015] The technical solution provided by this invention for the application of a grouting composite corrosion inhibitor for deep coal mine support anchor cables is as follows: Application of a grouting composite corrosion inhibitor for deep coal mine support anchor cables, the composite corrosion inhibitor being used in deep coal mine roadway support, tunnel engineering, underground engineering or marine engineering fields.

[0016] Preferably, the composite corrosion inhibitor is used as an anchor cable grouting material in deep coal mine roadways.

[0017] The fourth objective of this invention is to provide a method for using a composite corrosion inhibitor for grouting anchor cables in deep coal mines. This composite corrosion inhibitor adopts an internal mixing design, directly incorporating the corrosion inhibitor into the grouting material, thus avoiding the problem of easy peeling of the surface coating, while ensuring that the corrosion inhibitor is evenly distributed around the anchor cable.

[0018] The technical solution of the present invention for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables is as follows: A method for using a grouting composite corrosion inhibitor for anchor cables in deep coal mines includes the following steps: (1) Surface-modified nano Cr2O3, Na3PO4 and surface-modified nano ZnO are uniformly mixed into the grouting material, and C50 ordinary silicate cement is selected as the grouting material to prepare anchoring sample M. (2) Add 0.2% polycarboxylate superplasticizer to the anchoring sample M, inject deionized water, the water-cement ratio is 0.32, pre-treat with an ultrasonic disperser, and then mechanically stir at 2000 rpm to form a uniform suspension. (3) The suspension was injected into the mold and compacted by vibration to form a standard specimen of 40mm×40mm×40mm. The standard specimen was cured in a constant temperature and humidity curing room and then vacuum dried to obtain the anchoring specimen G.

[0019] Preferably, in step (2), the frequency of the ultrasonic disperser is 40kHz and the power is 500W; in step (3), the temperature of the constant temperature and humidity curing room is 20±1℃ and the relative humidity is ≥95%.

[0020] This invention uses C50 ordinary silicate cement as the grouting material, employs a Cr2O3+Na3PO4+ZnO composite corrosion inhibitor system, adds polycarboxylate superplasticizer and deionized water, and processes the mixture using an ultrasonic disperser and a high-speed mechanical mixer to ensure uniform mixing. Finally, the suspension is injected into a standard steel mold, and after vibration compaction, constant temperature and humidity curing, and vacuum drying, the anchoring sample G is obtained.

[0021] Beneficial effects: (1) This invention employs an inorganic (Cr2O3+Na3PO4+ZnO) corrosion inhibitor system. Through high-energy ball milling, silane coupling agent treatment, ultrasonic dispersion, and high-speed stirring, interfacial compatibility is enhanced, local concentration differences are avoided, and the corrosion inhibitor functions better. This composite corrosion inhibitor is designed to meet the corrosion protection needs of deep mine anchoring grouting materials, filling the technological gap in corrosion inhibitors specifically for high-mineralization underground engineering environments. It provides a novel protective solution for deep coal resource development and effectively expands the diversity of functional products.

[0022] (2) The composite corrosion inhibitor of the present invention fully utilizes its unique synergistic effect and multifunctional mechanism. Through underground working condition simulation test verification, the corrosion inhibitor has an electrochemical corrosion inhibition efficiency of more than 96% on anchoring mortar under the high temperature and humidity and complex stress coupling environment of deep coal mine. It can significantly delay the material deterioration process, extend the service life of the anchoring system, and effectively ensure the long-term reliability of the deep roadway support system.

[0023] (3) The composite corrosion inhibitor adopts an internal doping design, which directly incorporates the corrosion inhibitor into the grouting material, avoiding the problem of easy peeling of the surface coating, while ensuring that the corrosion inhibitor is evenly distributed around the anchor cable. The composite corrosion inhibitor of the present invention is not only suitable for deep coal mine roadway support, but can also be extended to other highly corrosive environments, such as tunnel engineering, underground engineering, marine engineering and other fields. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein: Figure 1 For flowcharts; Figure 2 A comparison chart of the test results of anchorage specimens G1, G2, G3, and CG in the compressive strength test. Figure 3 The potentiodynamic polarization curves of anchor cable specimens G1, G2, G3, and CG are shown. Figure 4 Electrochemical impedance spectroscopy of anchor cable specimens G1, G2, G3, and CG. Detailed Implementation

[0025] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will understand that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0026] Example 1 The preparation of pretreated anchor cable specimens includes the following steps: 1) Select a high-strength prestressed anchor cable component that meets the requirements of GB / T5224-2014. The anchor cable component has a yield strength of 1700MPa and an ultimate tensile strength of 2180MPa. It is made of 19 strands of steel wire and has a characteristic diameter of 22mm after equivalent section conversion.

[0027] 2) The base material is processed into 10mm diameter pieces using an electrical discharge wire cutting machine. 3 Standard cubic specimens were cut and then subjected to ultrasonic cleaning (frequency 40kHz, power 120W) and constant temperature drying treatment (105℃±2℃, continuous drying until constant quality).

[0028] 3) Specimen pretreatment includes conductive connection and interface encapsulation processes: After reliably connecting the top of the specimen to the copper wire, it is fixed in the cavity of a special mold, and the effective working area of ​​the bottom surface is controlled to be 1 cm². 2 Silicone is used to seal the interface.

[0029] 4) The working surface is treated with fully automatic metallographic grinding equipment to carry out gradient polishing: 600 grit, 800 grit and 1200 grit silicon carbide sandpaper are used in stages to grind the surface in sequence, so that the working surface is smooth and there are no surface defects such as oxidation pits when visually inspected.

[0030] 5) After the surface treatment is completed, the specimens are rinsed alternately with deionized water and anhydrous ethanol, then transferred to a vacuum drying oven for drying (60°C), and finally sealed in a vacuum storage device under an argon atmosphere for later use.

[0031] Example 2 A method for using a grouting composite corrosion inhibitor for anchor cables in deep coal mine support (preparation of anchorage specimen G1 and anchor cable specimen G1) includes the following steps: S1. Nano-sizing treatment: Cr2O3 and ZnO powders were placed separately in a high-energy ball mill using 5mm diameter zirconia balls as the grinding medium, with the ball-to-powder ratio strictly controlled at 10:1. Under nitrogen protection (purity ≥99.99%), the powders were ball-milled at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size ≤200nm. During the ball milling process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0032] S2. Surface modification treatment: Nano-Cr2O3 powder and nano-ZnO powder were dispersed separately in 60 ml of ethanol solution (95% concentration) containing 1 wt.% silane coupling agent (KH-550). Then, they were ultrasonically treated for 30 min using an ultrasonic cleaner (200 W power, 40 kHz frequency) to ensure sufficient particle dispersion and surface modification. Subsequently, the suspensions were dried in a vacuum drying oven at 60℃ (vacuum degree ≤0.1 MPa) for 12 h to obtain surface-modified nano-Cr2O3 powder and surface-modified nano-ZnO powder, respectively.

[0033] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, weigh the surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO respectively, select C50 ordinary silicate cement as grouting material, and make anchoring sample M1.

[0034] Add 0.2% polycarboxylate superplasticizer to anchoring sample M1 and inject deionized water, strictly controlling the water-cement ratio at 0.32. Pre-treat the mixture for 20 min using an ultrasonic disperser (40 kHz, 500 W), then stir for 1 h using a high-speed mechanical mixer (2000 rpm) to form a homogeneous suspension. Monitor the dispersion effect of the suspension using a laser particle size analyzer to ensure uniform particle distribution and no agglomeration.

[0035] S4. Grouting, Molding, and Curing: The suspension is injected into a standard 40mm×40mm×40mm steel mold and compacted using a vibrating table (frequency 50Hz, amplitude 0.5mm) for 2 minutes to remove air bubbles. After molding, the standard specimen is placed in a constant temperature and humidity curing room (temperature 20±1℃, relative humidity ≥95%) for 7 days. During curing, the humidity and temperature of the specimen are checked regularly every day to ensure a stable curing environment. After curing, the specimen is placed in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to obtain anchorage specimen G1. The compressive strength of the specimen is tested using a compressive strength tester to ensure that its mechanical properties meet the requirements. The process is as follows: Figure 1 As shown.

[0036] S5. Crushing and Impregnation: 300g of crushed sample (≤5mm particle size) from the 7-day-old anchorage specimen G1 was crushed and placed in a sealed extraction container. 500ml of deionized water was added at a solid-liquid ratio of 1:1.67. The sample was then shaken and impregnated at a constant temperature of 25℃ for 48 hours (frequency 2Hz). The mixture was then filtered through a 0.45μm filter membrane to obtain simulated pore liquid. The pretreated anchorage specimen was immersed in the extraction liquid for 48 hours to establish a corrosive medium contact interface, thus obtaining anchorage specimen G1. This specimen was then transferred to an argon-protected environment for storage and subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0037] Table 1 shows the formulation of the composite corrosion inhibitor for anchor cable grouting in the examples. Example 3 A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables (preparation of anchorage sample G2) includes the following steps: S1. Nano-sizing treatment: Cr2O3 and ZnO powders were placed separately in a high-energy ball mill using 5mm diameter zirconia balls as the grinding medium, with the ball-to-powder ratio strictly controlled at 10:1. Under nitrogen protection (purity ≥99.99%), the powders were ball-milled at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size ≤200nm. During the nano-sizing process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0038] S2. Surface modification treatment: Nano-Cr2O3 powder and nano-ZnO powder were dispersed in 60 ml of ethanol solution (concentration 95%) containing 1 wt.% silane coupling agent (KH-550). The solution was ultrasonically treated for 30 min using an ultrasonic cleaner (power 200W, frequency 40kHz) to ensure sufficient particle dispersion and surface modification. Subsequently, the suspension was dried in a vacuum drying oven at 60℃ (vacuum degree ≤0.1MPa) for 12 h to obtain surface-modified nano-Cr2O3 powder and surface-modified nano-ZnO powder.

[0039] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, weigh the surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO respectively, select C50 ordinary silicate cement as grouting material, and make anchoring sample M2.

[0040] Add 0.2% polycarboxylate superplasticizer to anchoring sample M2, and inject deionized water, strictly controlling the water-cement ratio at 0.32. Pre-treat the mixture for 20 min using an ultrasonic disperser (40 kHz, 500 W), then stir for 1 h using a high-speed mechanical mixer (2000 rpm) to form a homogeneous suspension. Monitor the dispersion effect of the suspension using a laser particle size analyzer to ensure uniform particle distribution and no agglomeration.

[0041] S4. Grouting and Curing: The suspension is injected into a standard 40mm×40mm×40mm steel mold and compacted using a vibrating table (frequency 50Hz, amplitude 0.5mm) for 2 minutes to remove air bubbles. After molding, the standard specimen is placed in a constant temperature and humidity curing room (temperature 20±1℃, relative humidity ≥95%) for 7 days. During curing, the humidity and temperature of the specimen are checked regularly every day to ensure a stable curing environment. After curing, the specimen is placed in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to obtain anchorage specimen G2. The compressive strength of the specimen is tested using a compressive strength tester to ensure that its mechanical properties meet the requirements.

[0042] S5. Crushing and Impregnation: 300g of crushed sample (≤5mm particle size) from the 7-day-old anchorage specimen G2 was crushed and placed in a sealed extraction container. 500ml of deionized water was added at a solid-liquid ratio of 1:1.67. The sample was then shaken and impregnated at a constant temperature of 25℃ for 48 hours (frequency 2Hz). The mixture was then filtered through a 0.45μm filter to obtain simulated pore liquid. The pretreated anchorage specimen was immersed in the extraction liquid for 48 hours to establish a corrosive medium contact interface, thus obtaining anchorage specimen G2. This specimen was then transferred to an argon-protected environment for storage and subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0043] Example 4 A method for using a grouting composite corrosion inhibitor for deep coal mine support anchor cables (preparation of anchorage sample G3) includes the following steps: S1. Nano-sizing treatment: Cr2O3 and ZnO powders were placed separately in a high-energy ball mill using 5mm diameter zirconia balls as the grinding medium, with the ball-to-powder ratio strictly controlled at 10:1. Under nitrogen protection (purity ≥99.99%), the powders were ball-milled at 300 rpm for 4 hours to obtain nano-Cr2O3 and nano-ZnO powders with a particle size ≤200nm. During the nano-sizing process, a 10-minute pause was taken every 30 minutes to avoid local overheating and ensure the uniformity and stability of the nanoparticles.

[0044] S2. Surface modification treatment: Nano-Cr2O3 powder and nano-ZnO powder were dispersed in an ethanol solution (95% concentration) containing 60 ml of 1 wt.% silane coupling agent (KH-550). The solution was ultrasonically treated for 30 min using an ultrasonic cleaner (200 W, 40 kHz) to ensure sufficient particle dispersion and surface modification. Subsequently, the suspension was dried in a vacuum drying oven at 60 °C (vacuum degree ≤ 0.1 MPa) for 12 h to obtain surface-modified nano-Cr2O3 powder and surface-modified nano-ZnO powder.

[0045] S3, corrosion inhibitor composite and gradient dispersion, according to Table 1, surface modified nano Cr2O3, Na3PO4 and surface modified nano ZnO were weighed respectively, and C50 ordinary silicate cement was selected as grouting material to prepare anchoring sample M3.

[0046] Add 0.2% polycarboxylate superplasticizer to anchoring sample M3 and inject deionized water, strictly controlling the water-cement ratio at 0.32. Pre-treat the mixture for 20 min using an ultrasonic disperser (40 kHz, 500 W), then stir for 1 h using a high-speed mechanical mixer (2000 rpm) to form a homogeneous suspension. Monitor the dispersion effect of the suspension using a laser particle size analyzer to ensure uniform particle distribution and no agglomeration.

[0047] S4. Grouting and Curing: The suspension is injected into a standard steel mold (40mm×40mm×40mm) and compacted using a vibrating table (50Hz frequency, 0.5mm amplitude) for 2 minutes to remove air bubbles. After molding, the standard specimen is placed in a constant temperature and humidity curing room (temperature 20±1℃, relative humidity ≥95%) for 7 days. During curing, the humidity and temperature of the specimen are checked regularly every day to ensure a stable curing environment. After curing, the specimen is placed in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to obtain anchorage specimen G3. The compressive strength of the specimen is tested using a compressive strength tester to ensure that its mechanical properties meet the requirements.

[0048] S5. Crushing and Impregnation: 300g of crushed sample (≤5mm particle size) from the 7-day-old anchorage specimen G3 was crushed and placed in a sealed extraction container. 500ml of deionized water was added at a solid-liquid ratio of 1:1.67. The sample was then shaken and impregnated at a constant temperature of 25℃ for 48 hours (frequency 2Hz). The mixture was then filtered through a 0.45μm filter to obtain a simulated pore liquid. The pretreated anchorage specimen was immersed in the extraction liquid for 48 hours to establish a corrosive medium contact interface, thus obtaining anchorage specimen G3. This specimen was then transferred to an argon-protected environment for storage and subsequent Tafel polarization curve and electrochemical impedance spectroscopy testing.

[0049] Example 5 The preparation of anchorage specimens CG and anchor cable specimens CG includes the following steps: S1. Grouting and Curing: C50 ordinary Portland cement was selected as the grouting material. The grouting material was injected into a standard steel mold (40mm×40mm×40mm) and compacted using a vibrating table (50Hz frequency, 0.5mm amplitude) for 2 minutes to remove air bubbles. After molding, the standard specimens were placed in a constant temperature and humidity curing room (temperature 20±1℃, relative humidity ≥95%) for 7 days. During the curing process, the humidity and temperature of the specimens were checked regularly every day to ensure a stable curing environment. After curing, the specimens were placed in a vacuum drying oven (vacuum degree ≤0.1MPa) for 24 hours to obtain the anchoring sample CG. The compressive strength of the specimens was tested using a compressive strength tester to ensure that their mechanical properties met the requirements.

[0050] S2, impregnation: collect in-situ seepage from deep mines, and after dynamic impregnation of the pretreated anchor cable specimens for 48 hours, obtain anchor cable sample CG, which is then transferred to an argon-protected environment for storage for subsequent Tafel polarization curve and electrochemical impedance spectroscopy tests.

[0051] Characterization and Analysis: (1) Strength test The compressive strength of anchorage specimens G1, G2, G3 and the control anchorage specimen CG were tested respectively, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that after 1 day of curing, the compressive strength of anchor specimens G2 and G3 was lower than that of the control group anchor specimen CG. However, after 7 days of curing, the compressive strength of anchor specimen G1 was slightly higher than that of the control group anchor specimen CG. Therefore, it can be inferred that the corrosion inhibitor has no adverse effect on anchor solidification and strength after 7 days of normal curing, and the slightly higher strength of anchor specimen G1 compared to the control group anchor specimen CG is consistent with the high-strength characteristics of anchor cable support in deep coal mines, making it a suitable corrosion inhibitor.

[0052] (2) Potentiodynamic polarization curve test Potential dynamic polarization curves were tested on anchor cable specimen G1 from Example 2, anchor cable specimen G2 from Example 3, anchor cable specimen G3 from Example 4, and anchor cable specimen CG from the control group from Example 5. The results are as follows: Figure 3 As shown.

[0053] Depend on Figure 3 The corrosion inhibition performance evaluation based on polarization curve testing shows that the composite corrosion inhibitor has a significant regulatory effect on the electrochemical behavior of the anchored specimens. Electrochemical test data show that the anchor specimens G1-G3 modified with the corrosion inhibitor exhibit a significant positive shift in corrosion potential compared to the control group, with an average anodic polarization amplitude of 0.16V, indicating that the thermodynamic corrosion tendency of the material surface is effectively controlled. Further kinetic parameter analysis shows that the corrosion current density of the corrosion inhibitor-treated groups shows an order-of-magnitude decrease, with anchor specimen G1 exhibiting the best corrosion inhibition performance, its current density value decreasing from the initial 2.29 × 10⁻⁶.-4 A / cm 2 Significantly reduced to 8.52×10 -6 A / cm 2 The corrosion rate attenuation coefficient reached 96.3%. This numerical comparison fully verifies the key role of composite corrosion inhibitors in the metal passivation process, and its corrosion inhibition performance is significantly better than that of conventional single corrosion inhibitor systems.

[0054] (3) Electrochemical impedance spectroscopy test Electrochemical impedance spectroscopy (EIS) is a key technique for studying electrochemical systems. It involves measuring the system's response to AC signal perturbations at different frequencies to obtain impedance information. A three-electrode system is commonly used. A small AC voltage is superimposed on a DC potential and applied between the working and reference electrodes. The AC current at the working electrode is measured, and the data is recorded by varying the frequency to obtain the electrochemical impedance spectrum. The data is presented as Nyquist and Bode plots, and circuit component parameters such as resistance and capacitance are obtained through equivalent circuit fitting. These parameters reflect the physicochemical processes of the system. EIS is widely used in research fields such as batteries, corrosion, electrocatalysis, and sensors, providing crucial information for related studies.

[0055] The CS310 electrochemical workstation manufactured by Wuhan Koster was used. The reference electrode and auxiliary electrode were a saturated calomel electrode and a platinum wire, respectively. To ensure the applicability of the invention, the conductive solution was water sprayed from the roof of a coal mine. Tests were conducted at a frequency interval of 0.01-100000Hz with an amplitude of ±3mV at the self-corrosion potential.

[0056] An equivalent circuit is fitted to the sample, where Rs is the solution resistance, Rf is the double-layer capacitance, CPEf is the protective film capacitance, and Rct is the charge transfer resistance. Figure 4 The middle curve is the Nyquist plot of electrochemical impedance spectroscopy, from... Figure 4 It can be seen that the impedance radius of anchor cable specimens G1, G2, and G3 is significantly larger than that of the control group anchor cable specimen CG. Since the increase in impedance radius indicates the improvement in corrosion resistance, it proves that anchor cable specimens G1, G2, and G3 have better corrosion resistance and the corrosion inhibitor plays a better role.

[0057] The corrosion inhibitor Cr2O3+Na3PO4+ZnO significantly reduced the corrosion rate of anchoring materials through a synergistic effect of multiple mechanisms. Its corrosion inhibition mechanism can be systematically analyzed from aspects such as passivation film formation, adsorption film formation, cathodic inhibition, and synergistic effects. Firstly, the passivation film formation and self-healing mechanism of Cr2O3 allows nano-Cr2O3 to react with Fe on the anchor cable surface in an alkaline grouting environment (pH≈12) to form a dense Cr(OH)3 or Cr2O3·nH2O passivation film, effectively blocking Cl... - SO4 2-The penetration of corrosive ions is prevented. Silane coupling agent modification enhances the interfacial bonding between Cr2O3 and the grouting matrix, preventing particle agglomeration and ensuring uniform passivation film coverage. Therefore, in the event of localized damage, Cr... 3+ The passivation layer is rapidly regenerated through redox reactions, maintaining the integrity of the film.

[0058] In addition, the dual effects of adsorption and precipitation of Na3PO4 lead to the hydrolysis of Na3PO4 to generate PO4. 3- Ions, with Fe 2+ The precipitate forms an insoluble FePO4, which covers the anolyte active sites and blocks the anolyte reaction. 3- The formation of a monolayer on the metal surface through chemisorption (Langmuir model) inhibits the oxygen reduction reaction (cathodic process) and reduces the corrosion current density. Na3PO4 acts as a dispersion carrier, promoting the uniform distribution of Cr2O3 and ZnO and optimizing the interfacial microenvironment.

[0059] Cathodic protection and physical barrier effect of ZnO: Dissolution and release of Zn from nano-ZnO 2+ In the cathode region, with OH - The reaction generates a Zn(OH)2 precipitate film, which inhibits oxygen diffusion and cathodic reduction. ZnO particles fill the pores of the grouting material, reducing the permeability of the medium and forming a physical barrier to delay the diffusion of corrosive media. Furthermore, modified ZnO and Cr2O3 form a "membrane-membrane interlocking" structure through hydrogen bonding, improving overall density.

[0060] The synergistic effect among the three components includes spatial complementarity: Cr2O3 covers the anodic region, ZnO suppresses the cathodic region, and Na3PO4 fills interfacial defects, forming a full-surface protective network. It also includes electrochemical coupling: the passivation potential of Cr2O3 (+0.16V) and the cathodic polarization effect of ZnO synergistically reduce the corrosion driving force. The synergistic effect further strengthens the structure, dispersing nanoparticles within the grout matrix, increasing material density, and reducing the penetration path of corrosive media.

[0061] In this patent, the synergistic effect of Cr2O3, Na3PO4, and ZnO is key to its significantly improved corrosion inhibition effect. The three work together to form a multi-layered protective mechanism: Cr2O3 protects the anodic region through a passivation film, Na3PO4 protects the entire surface through adsorption and precipitation films, and ZnO reduces corrosion current by inhibiting cathodic reactions. This synergistic effect not only optimizes the microenvironment of the metal surface and reduces Cl... - The concentration of corrosive ions can also optimize the internal structure of the material to a certain extent, improving the strength and durability of the anchoring material. The corrosion inhibitor has good compatibility with the grouting material, does not affect the solidification process, and can further enhance the overall performance of the material through structural optimization.

[0062] In summary, the corrosion inhibitor Cr2O3+Na3PO4+ZnO significantly reduces the corrosion rate of anchoring materials through multiple mechanisms, including passivation film formation, adsorption film formation, cathodic inhibition, and synergistic corrosion inhibition. Its excellent corrosion inhibition performance and good compatibility make it a promising candidate for application in deep coal mine environments. Through in-depth research and optimization, this corrosion inhibitor is expected to become an important solution for corrosion protection of anchoring materials used in deep coal mine grouting. Comprehensive evaluation shows that anchoring specimen G1 exhibits the best corrosion resistance; therefore, the optimal corrosion inhibitor ratio is Cr2O3+Na3PO4(A+B) 0.5%+0.1% (1kg grouting material + 5g reagent A + 1g reagent B).

[0063] The present invention exhibits significant technical advantages. By nano-sizing and surface modification of the corrosion inhibitor raw materials, as well as optimizing the compounding and dispersion processes, the uniformity and stability of the corrosion inhibitor's dispersion in the grouting material are effectively improved, ensuring that the corrosion inhibitor can fully exert its function and enhancing the protective performance of the anchor cable anchoring specimens. Simultaneously, strict control of parameters in each preparation stage ensures that the mechanical properties of the specimens meet the requirements, providing a more reliable protection solution for deep coal mine support.

[0064] The addition of a corrosion inhibitor significantly reduced the corrosion rate of the anchor cable specimens, specifically manifested in an increased impedance radius, a decreased corrosion current density, and improved surface morphology. Electrochemical impedance spectroscopy (EIS) showed a significant increase in the impedance radius of the specimens with the added corrosion inhibitor, indicating a significant improvement in their corrosion resistance. Polarization curve analysis showed a significant decrease in the corrosion current density of the specimens with the added corrosion inhibitor, indicating that the inhibitor effectively suppressed the corrosion reaction. Scanning electron microscopy (SEM) revealed a significant reduction in corrosion products on the surface of the specimens with the added corrosion inhibitor, resulting in a more uniform and dense surface morphology. These experimental results fully validate the effectiveness of the corrosion inhibitor.

[0065] From an application perspective, this corrosion inhibitor boasts advantages such as simple formulation, low cost, and good compatibility, making it suitable for corrosion protection of anchoring materials used in deep coal mine grouting. Its multiple protection mechanisms and synergistic corrosion inhibition effect can significantly extend the service life of anchoring materials, ensuring the safety and stability of deep coal mining. Future research can further optimize the formulation and addition ratio of the corrosion inhibitor to improve its corrosion inhibition effect and economic efficiency.

[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A grouting composite corrosion inhibitor for anchor cables used in deep coal mine support, characterized in that, The composite corrosion inhibitor is composed of Na3PO4, surface-modified nano-Cr2O3, and surface-modified nano-ZnO. The mass ratio of Na3PO4, surface-modified nano-Cr2O3, and surface-modified nano-ZnO is 1-10:5:1-10. The surface-modified nano-Cr2O3 and surface-modified nano-ZnO are prepared by dispersing nano-Cr2O3 and nano-ZnO separately in an organic solution containing a silane coupling agent, followed by ultrasonic treatment and drying.

2. A method for preparing a grouting composite corrosion inhibitor for deep coal mine support anchor cables as described in claim 1, characterized in that, Includes the following steps: S1. Nano-sizing treatment: Cr2O3 and ZnO powders are ball-milled under inert gas protection to obtain nano-Cr2O3 and nano-ZnO. S2. Surface modification treatment: Nano Cr2O3 and nano ZnO are dispersed in an organic solution containing a silane coupling agent, ultrasonically treated, and then dried to obtain surface-modified nano Cr2O3 and surface-modified nano ZnO. S3. Preparation of composite corrosion inhibitor: Na3PO4, surface-modified nano-Cr2O3 and surface-modified nano-ZnO are mixed to prepare a composite corrosion inhibitor.

3. The preparation method of the grouting composite corrosion inhibitor for deep coal mine support anchor cables according to claim 2, characterized in that, In step S1, Cr2O3 and ZnO powders are placed in a ball mill, with zirconia balls as the medium and a ball-to-material ratio of 10:

1. The mixture is ball-milled at 300 rpm for 4 hours under inert gas protection to obtain nano-Cr2O3 and nano-ZnO with a particle size ≤200 nm.

4. The preparation method of the grouting composite corrosion inhibitor for deep coal mine support anchor cables according to claim 3, characterized in that, In step S2, nano-Cr2O3 and nano-ZnO are dispersed in an ethanol solution containing 1 wt.% silane coupling agent, ultrasonically treated for 30 min, and then dried at 60 °C to obtain surface-modified nano-Cr2O3 and surface-modified nano-ZnO.

5. The application of the grouting composite corrosion inhibitor for deep coal mine support anchor cables as described in claim 1, characterized in that, The composite corrosion inhibitor is used in deep coal mine roadway support, tunnel engineering, or marine engineering.

6. The application of the grouting composite corrosion inhibitor for deep coal mine support anchor cables as described in claim 5, characterized in that, The composite corrosion inhibitor is used as a grouting material for anchor cables in deep coal mine roadways.

7. A method for using the grouting composite corrosion inhibitor for deep coal mine support anchor cables as described in claim 1, characterized in that, Includes the following steps: (1) Na3PO4, surface-modified nano Cr2O3 and surface-modified nano ZnO are uniformly added to the grouting material, and C50 ordinary silicate cement is selected as the grouting material to prepare anchoring sample M. (2) Add 0.2% polycarboxylate superplasticizer to the anchoring sample M, inject deionized water, the water-cement ratio is 0.32, pre-treat with an ultrasonic disperser, and then mechanically stir at 2000 rpm to form a uniform suspension. (3) The suspension was injected into the mold and compacted by vibration to form a standard specimen of 40mm×40mm×40mm. The standard specimen was cured in a constant temperature and humidity curing room and then vacuum dried to obtain the anchoring specimen G.

8. The method of using the grouting composite corrosion inhibitor for deep coal mine support anchor cables according to claim 7, characterized in that, In step (2), the frequency of the ultrasonic disperser is 40kHz and the power is 500W; in step (3), the temperature of the constant temperature and humidity curing room is 20±1℃ and the relative humidity is ≥95%.

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