A hot sludge micro-powder synergistic zinc phosphate two-component epoxy anticorrosive coating, and a preparation method and application thereof

Abstract

The application discloses a kind of hot sludge micro powder cooperates zinc phosphate two-component epoxy anticorrosive coating and its preparation method and application, belong to the technical field of functional coating, the application is realized by the synergistic complementation of hot sludge micro powder and zinc phosphate in particle size scale, morphology feature, the gradient dense filling structure of " rough and thin complementation " inside coating, simultaneously with the chemical passivation effect of zinc phosphate and the physical shielding effect of hot sludge, the hardness, adhesion, flexibility and long-acting anticorrosive performance of coating are significantly improved.The application realizes metallurgical solid waste resource utilization, and greatly reduces coating cost, and is suitable for the anticorrosion coating of metal base material in the field such as marine engineering, petroleum chemical industry.

Description

Technical Field

[0001] This invention belongs to the technical field of functional coatings, specifically relating to a two-component epoxy anti-corrosion coating of hot-pressed slag micro powder and zinc phosphate, its preparation method and application. Background Technology

[0002] Epoxy resin coatings are widely used for corrosion protection of metal substrates in marine engineering, petrochemicals, and transportation due to their excellent adhesion, chemical resistance, and mechanical strength. Traditional epoxy anti-corrosion coatings often use zinc powder, chromates, or phosphates as active rust inhibitors and fillers. Among them, zinc phosphate has become the mainstream choice to replace toxic chromates because it is non-toxic, environmentally friendly, and has good passivation and corrosion inhibition capabilities. However, the single zinc phosphate filler system still has the following shortcomings in practical applications: zinc phosphate particles themselves have high hardness but are also brittle; excessive addition can lead to decreased coating flexibility, stress concentration, and easy formation of microcracks; the dispersibility and interfacial compatibility of zinc phosphate in the coating are limited, making it difficult to form a completely dense physical barrier layer, and corrosive media can still slowly penetrate under long-term immersion conditions; high-purity zinc phosphate is expensive, and large-scale use is not conducive to cost reduction and efficiency improvement in industrial applications.

[0003] Meanwhile, a large amount of hot slag (a type of steel slag stabilized by hot slag quenching) generated during steel smelting has long been disposed of through stockpiling, which not only occupies land resources but also poses environmental safety hazards. Hot slag micronized powder contains abundant active oxide components such as calcium, iron, and silicon, exhibiting certain hydration activity and micro-aggregate filling effect; however, its application in organic coatings has not been fully developed. Current technologies lack technical solutions for using hot slag micronized powder as an auxiliary functional filler in synergy with zinc phosphate in epoxy anti-corrosion coating systems, and there is a lack of systematic research on the impact of adjusting the ratio of the two on the coating's microstructure and overall mechanical-anti-corrosion performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a two-component epoxy anti-corrosion coating with hot slag micro powder and zinc phosphate, its preparation method and application, so as to solve the problems mentioned in the background art or achieve better technical effects.

[0005] To solve the above-mentioned technical problems, the inventors, through practice and summarization, derived the technical solution of this invention. This invention discloses a two-component epoxy anti-corrosion coating for hot-quenching slag micron powder and zinc phosphate synergistic, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0006] 72-120 parts hot-pressed residue powder, 36 parts talc powder, 24-72 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0007] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0008] Furthermore, the particle size of the hot-curing slag powder is 800 mesh, and the hot-curing slag contains Al2O3+CaO+Fe x O≥65%.

[0009] Furthermore, the zinc phosphate has a particle size of 800 mesh; the zinc phosphate minerals include: zinc phosphate tetrahydrate, zinc phosphate dihydrate, and elemental zinc.

[0010] Furthermore, the wetting and dispersing stabilizer is a polyurethane block-modified polycarboxylic acid polymer copolymer, model XYS-6800; the anti-settling agent is a modified polyurea, obtained from polyurea-branched monoalkylamine, model 410L; the leveling agent is a polyether-modified siloxane, model XYS-5313; and the defoamer is a polyether-modified siloxane, model XYS-6550.

[0011] Furthermore, the epoxy resin solution is prepared by mixing epoxy resin and xylene-n-butanol composite solvent at a mass ratio of 1:1, wherein the mass ratio of xylene to n-butanol is 7:3.

[0012] Furthermore, the preparation method of any of the above-mentioned hot-quenching slag micro-powder synergistic zinc phosphate two-component epoxy anti-corrosion coatings includes the following steps:

[0013] S1: Place the hot-cured residue powder in a 105℃ oven for 6 hours to remove moisture, then remove and set aside.

[0014] S2: Prepare an epoxy resin solution by mixing epoxy resin and xylene-n-butanol composite solvent at a mass ratio of 1:1. Then, add the epoxy resin solution to a stirring tank and add wetting and dispersing stabilizer, anti-settling agent, leveling agent and defoamer in sequence. Stir and disperse for 15 minutes after each material is added.

[0015] S3: Add talc powder, zinc phosphate and hot slag powder pretreated in S1 to the S2 mixing tank, then add glass beads and increase the speed to 1200 r / min for grinding for 4 hours. Finally, filter the mixture to obtain a two-component epoxy anti-corrosion coating of hot slag powder and zinc phosphate.

[0016] Furthermore, in step S3, during the grinding process, the fineness is measured every 30 minutes using a scraper fineness gauge, and grinding is stopped when the fineness reaches below 35 μm.

[0017] The application of any of the above-mentioned hot slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coatings in the anti-corrosion coating of carbon steel and tinplate metal substrates in marine engineering, petrochemical or transportation fields.

[0018] Furthermore, the application method is as follows:

[0019] S1: Use a small sanding belt with a roughness of 250 mesh and a size of 330×10mm to perform two full grindings on the surface of the tinplate substrate. The grinding direction is the same each time and the two grinding directions are perpendicular to each other to remove surface rust products, oxide layer and impurities.

[0020] S2: After polishing, wipe and clean the surface of the tinplate with anhydrous ethanol and deionized water in turn, and then let it air dry naturally for later use.

[0021] S3: Use a coater to evenly apply the coating to the surface of the pretreated tinplate to form a coating with a thickness of 100μm;

[0022] S4: Place the coated sample in a 25°C room temperature environment for 3-5 days to allow the coating to fully cure and form a stable anti-corrosion coating.

[0023] Furthermore, the anti-corrosion coating has a hardness of 2H, an adhesion grade of 0, a flexibility of 13mm, a 7-day water absorption rate of 0.22wt.%, and an impedance modulus of 1.55×10 at a frequency of 0.01Hz. 7 Ω·cm 2 The corrosion potential is -0.04V, and the corrosion current density is 2.78×10⁻⁶. -7 A·cm -2 The contact angle is 85.56°.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention achieves a good balance between hardness, flexibility and adhesion by complementing the particle size of hot slag micro powder (irregular rigid particles) and zinc phosphate (high hardness filler) and synergistic spatial filling. The porosity of the coating is significantly reduced, the density is improved, the hardness reaches 2H, the adhesion is grade 0, and the flexibility is optimized to 13mm. This overcomes the defect of poor flexibility (20mm) of single zinc phosphate coating and overcomes the defect of poor flexibility (20mm).

[0026] (2) The hot slag micro powder of the present invention fills the gaps in the zinc phosphate network, extending the diffusion path of the corrosive medium; the zinc phosphate forms a dense phosphate conversion film at the substrate interface, which, in conjunction with the physical shielding effect of the hot slag, increases the coating impedance modulus to 1.55×10. 7 Ω·cm 2 The corrosion potential shifted positively to -0.04V, and the corrosion current density dropped to 2.78×10⁻⁶. -7 A·cm -2 It has a water absorption rate of only 0.22 wt.% after 7 days, and a salt spray resistance time of up to 168 hours without bubbling. Its overall anti-corrosion effect is significantly better than that of the pure zinc phosphate system.

[0027] (3) The hot slag micro powder (main skeleton) and zinc phosphate (micro gap filler) of the present invention form a multi-level stack in terms of particle size and morphology. Combined with the sheet-like barrier effect of talc, the coating is made dense in stages of "macropore-medium pore-micropore". At the same time, the surface roughness of the hot slag improves the hydrophobicity of the coating (contact angle reaches 85.56°) and zinc phosphate optimizes the chemical bonding of the interface. The two work together to give the coating a triple protection mechanism of "physical shielding + chemical passivation + interface enhancement".

[0028] (4) This invention replaces part of the high-cost zinc phosphate filler with inexpensive hot slag powder, thereby reducing the cost of raw materials while ensuring or even improving the anti-corrosion performance. At the same time, it provides a feasible technical solution for the high-value utilization of steel smelting waste slag, and has significant environmental and economic benefits. Attached Figure Description

[0029] Figure 1 The XRD patterns are of the hot slag (YG) and zinc phosphate (LX) used as raw materials in this invention.

[0030] Figure 2 This is a schematic diagram of the electrochemical three-electrode test of the present invention;

[0031] Figure 3 This is a comparison chart of the salt spray resistance test results of the epoxy anticorrosion coatings obtained in Examples 1-5 of the present invention and Comparative Example 1;

[0032] Wherein, (a) is Comparative Example 1; (b) is Example 1; (c) is Example 2; (d) is Example 3; (e) is Example 4; and (f) is Example 5;

[0033] Figure 4 These are surface morphology images of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 before salt water immersion.

[0034] Wherein, (a) is Comparative Example 1; (b) is Example 1; (c) is Example 2; (d) is Example 3; (e) is Example 4; and (f) is Example 5;

[0035] Figure 5 These are morphological images of the salt water immersion test results of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of the present invention.

[0036] Wherein, (a) is Comparative Example 1; (b) is Example 1; (c) is Example 2; (d) is Example 3; (e) is Example 4; and (f) is Example 5;

[0037] Figure 6 This is a trend chart showing the 7-day water absorption rate of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of the present invention.

[0038] Figure 7 The contact angle test results of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of this invention;

[0039] Figure 8 The contact angle diagrams are shown for the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of the present invention.

[0040] Wherein, (a) is Comparative Example 1; (b) is Example 1; (c) is Example 2; (d) is Example 3; (e) is Example 4; and (f) is Example 5;

[0041] Figure 9 Bode spectra of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of this invention;

[0042] Figure 10 The figures show the Tafel curve test results of the epoxy anticorrosion coatings obtained in Examples 1-5 and Comparative Example 1 of this invention.

[0043] Figure 11 The images shown are surface SEM images of the epoxy anti-corrosion coatings obtained in Examples 1-5 and Comparative Example 1 of this invention.

[0044] Wherein, (a) is Comparative Example 1; (b) is Example 1; (c) is Example 2; (d) is Example 3; (e) is Example 4; and (f) is Example 5;

[0045] Figure 12 The above are schematic diagrams illustrating the anti-corrosion mechanism of the epoxy anti-corrosion coating obtained in Example 1 of Embodiments 1-5 of the present invention. Detailed Implementation

[0046] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0047] Unless otherwise specified, all raw materials or reagents used in the following examples are commercially available products.

[0048] Among them, the particle size of hot slag (YG) micro powder is 800 mesh, and the XRF test results are shown in Table 1 below;

[0049] Table 1. XRF test results of hot-pressed slag (YG) micro powder

[0050]

[0051] The talc powder (HSF) is industrial grade with a particle size of 1250 mesh; it was purchased from Liaoning Haiyu Company.

[0052] Zinc phosphate (LX) with a particle size of 800 mesh was purchased from Ma'anshan Caishiji Coatings Co., Ltd.

[0053] The epoxy resin (EP CYD-011) is sourced from Sinopec Baling Petrochemical Co., Ltd.

[0054] The wetting and dispersing stabilizer is a polyurethane block-modified polycarboxylic acid polymer copolymer, model: XYS-6800, electronic grade, sourced from Yunfeng Chemical Co., Ltd.

[0055] The anti-settling agent is a modified polyurea, made from polyurea-branched monoalkylamine, model number: 410L, electronic grade, sourced from Deyude Company;

[0056] The leveling agent, polyether-modified siloxane, is made from siloxane-branched polyether groups. Model: XYS-5313. It is an industrial grade product and is sourced from Yunfeng Chemical Co., Ltd.

[0057] The defoamer, polyether-modified siloxane, is made from siloxane-branched polyether groups. Model: XYS-6550, sourced from Yunfeng Chemical Co., Ltd.

[0058] The mechanical property testing of the epoxy anticorrosion coating prepared by this invention includes: hardness testing, adhesion grade determination, and flexibility testing. The testing methods are as follows:

[0059] Hardness Test: According to the national standard "Determination of Hardness of Coating Film by Pencil Test" (GB / T 6739-2006), the test procedure for the hardness of coating film by pencil is as follows: Fix the pencil in the testing instrument and let it slide at a constant speed on the surface of the test board. If visible scratches appear on the surface of the test board, the pencil with a lower hardness value should be replaced and the test repeated until no scratches appear.

[0060] Adhesion rating determination: Following the specifications in "Cross-cut Test for Paints and Varnishes" (GB / T 9286-2021), the adhesion of the paint was determined using an adhesion tester. The specific steps were as follows: The test plate was fixed horizontally, and a set of equidistant parallel lines were drawn using a cross-cut tester; after rotating the sample 90°, another set of vertical lines was drawn on it to form a grid. The damage or peeling condition of the paint in the grid area was observed using a magnifying glass, and evaluated according to the rating criteria in Table 2.

[0061] Table 2. Reference Standards for Coating Adhesion Test Results

[0062]

[0063] Flexibility Test: The flexibility of the coating is tested using a flexibility tester according to the "Determination of Flexibility of Coating Film" (GB / T 1731—2020). The test panel is fixed vertically, and a torque is applied to cause it to bend and deform. The diameter of the shaft that causes the coating to crack or peel off is recorded; this value characterizes the flexibility of the coating.

[0064] The corrosion resistance performance testing of the epoxy anticorrosion coating prepared by this invention includes: salt spray corrosion resistance test, salt immersion resistance test, hydrophobicity test, and electrochemical performance test. The test methods are as follows:

[0065] Salt spray corrosion resistance test: The test was conducted in accordance with the national standard GB / T 1771 "Determination of resistance to neutral salt spray of paints and varnishes", using a salt spray test chamber. The test chamber temperature was set at (35±2)℃, and the spray solution was sodium chloride solution.

[0066] Salt resistance test: The test was conducted according to the standard "Paints and Varnishes - Resistance to Liquid Media" (GB / T 1771-2007). All test panels were edge-sealed. The samples were then completely immersed in a 3.5 wt.% NaCl solution. Samples were removed every 24 hours, rinsed, and air-dried. Surface condition was recorded, and the water absorption rate of the coating was assessed by calculating the change in mass.

[0067] Hydrophobicity test: To evaluate the hydrophobic properties of the coating, the contact angle of the coating was measured using an OCA25 contact angle measuring instrument (CA) from Beijing Aodelino Instrument Co., Ltd. The test adopted the static water drop method, and to ensure the reliability of the data, five different locations were selected for measurement on each coating surface.

[0068] Electrochemical testing: The impedance response of the system is measured using a sinusoidal current; the quantitative relationship between impedance modulus and frequency is studied using Bode plots, and the corrosion current and corrosion potential are studied using Tafel plots. The effective test area of ​​the sample is 1 cm². 2 A three-electrode system was used, with a 3.5 wt.% NaCl solution as the electrolyte. A schematic diagram of the testing method is shown below. Figure 2 The frequency range is 10 5 ~10 -2 Hz.

[0069] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0070] 72-120 parts hot-pressed residue powder, 36 parts talc powder, 24-72 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0071] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0072] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is as follows:

[0073] S1: Place the hot-cured residue powder in a 105℃ oven for 6 hours to remove moisture, then remove and set aside.

[0074] S2: Prepare an epoxy resin solution by mixing epoxy resin and xylene-n-butanol composite solvent (the mass ratio of xylene to n-butanol is 7:3) at a mass ratio of 1:1. Then, add the epoxy resin solution to the stirring tank and add wetting and dispersing stabilizer, anti-settling agent, leveling agent and defoamer in sequence. Stir and disperse for 15 minutes after each material is added.

[0075] S3: Add talc powder and the hot slag powder pretreated in S1 to the mixing vessel in S2. Then add glass beads and increase the speed to 1200 r / min for grinding for 4 hours. During this period, the fineness is measured every 30 minutes using a scraper fineness meter (BGD 241 / 2). When the fineness reaches below 35 μm, stop grinding. Finally, filter the resulting mixture to obtain the hot slag powder synergistic zinc phosphate two-component epoxy anti-corrosion coating.

[0076] like Figure 1 As shown, the main minerals of zinc phosphate used in this invention include zinc phosphate tetrahydrate (Zn3(PO4)·4H2O), zinc phosphate dihydrate (Zn3(PO4)·2H2O), and elemental zinc (Zn). This phase structure endows zinc phosphate with good physical and chemical properties, and the zinc phosphate particles can be stacked tightly to form a protective layer, which significantly improves the corrosion resistance and wear resistance of the matrix.

[0077] Example 1

[0078] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0079] 72 parts hot-pressed residue powder, 36 parts talc powder, 72 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0080] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0081] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is as follows:

[0082] S1: Place the hot-cured residue powder in a 105℃ oven for 6 hours to remove moisture, then remove and set aside.

[0083] S2: Prepare an epoxy resin solution by mixing epoxy resin and xylene-n-butanol composite solvent (the mass ratio of xylene to n-butanol is 7:3) at a mass ratio of 1:1. Then, add the epoxy resin solution to the stirring tank and add wetting and dispersing stabilizer, anti-settling agent, leveling agent and defoamer in sequence. Stir and disperse for 15 minutes after each material is added.

[0084] S3: Add talc powder, zinc phosphate, and hot slag powder pretreated in S1 to the S2 mixing vessel. Then add glass beads and increase the rotation speed to 1200 r / min for grinding for 4 hours. During this period, the fineness is measured every 30 minutes using a scraper fineness meter (BGD241 / 2). When the fineness reaches below 35 μm, stop grinding. Finally, filter the resulting mixture to obtain a two-component epoxy anti-corrosion coating of hot slag powder and zinc phosphate.

[0085] Example 2

[0086] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0087] 96 parts hot-pressed residue powder, 36 parts talc powder, 48 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0088] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0089] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is the same as in Example 1.

[0090] Example 3

[0091] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0092] 108 parts hot-pressed residue powder, 36 parts talc powder, 36 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0093] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0094] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is the same as in Example 1.

[0095] Example 4

[0096] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0097] 115 parts hot-pressed residue powder, 36 parts talc powder, 29 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0098] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0099] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is the same as in Example 1.

[0100] Example 5

[0101] A two-component epoxy anti-corrosion coating for hot-quenched slag micron powder and zinc phosphate, comprising mixed fillers, resin solution and additives, with the following amounts of each component by weight:

[0102] 120 parts hot-pressed residue powder, 36 parts talc powder, 24 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0103] Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

[0104] The preparation method of the above-mentioned hot-quenching slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating is the same as in Example 1.

[0105] Comparative Example 1

[0106] A zinc phosphate-based epoxy anti-corrosion coating comprises a mixture of fillers, a resin solution, and additives, with the following amounts of each component by weight:

[0107] 36 parts talc powder, 144 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer;

[0108] Among them, the mixed filler composed of talc and zinc phosphate accounts for 60% of the total amount of the components without additives.

[0109] The preparation method of the above-mentioned zinc phosphate-based epoxy anticorrosive coating includes the following steps:

[0110] S1: Prepare an epoxy resin solution by mixing epoxy resin and xylene-n-butanol composite solvent (the mass ratio of xylene to n-butanol is 7:3) at a mass ratio of 1:1. Then, add the epoxy resin solution to the stirring tank and add wetting and dispersing stabilizer, anti-settling agent, leveling agent and defoamer in sequence. Stir and disperse for 15 minutes after each material is added.

[0111] S2: Add zinc phosphate and talc to the mixing vessel S1, then add glass beads and increase the rotation speed to 1200 r / min for grinding for 4 hours. During this period, the fineness is measured every 30 minutes using a scraper fineness meter (BGD 241 / 2). When the fineness reaches below 35 μm, stop grinding. Finally, filter the resulting mixture to obtain zinc phosphate-based epoxy anti-corrosion coating.

[0112] Example 6

[0113] The application of a two-component epoxy anti-corrosion coating composed of hot-quenching slag micro-powder and zinc phosphate is as follows:

[0114] S1: Substrate pretreatment and polishing: Select tinplate as the substrate. First, use a small sanding belt with a roughness of 250 mesh and a size of 330*10mm to polish the substrate surface twice. The polishing direction is the same each time and the two polishing directions are perpendicular to each other to treat the surface, so as to remove the rust products, oxide layer and other impurities attached to the surface and ensure that the substrate surface reaches a smooth and flat state.

[0115] S2: After S1 polishing is completed, use anhydrous ethanol and deionized water to thoroughly wipe the surface of the tinplate in turn to remove residual polishing debris and impurities. Then place it in a clean environment to air dry naturally for later use.

[0116] S3: Coating application and curing: The coatings prepared in Examples 1 to 5 above are uniformly applied to the surface of the pretreated tinplate using a coating applicator to form a coating with a thickness of 100 μm.

[0117] S4: After S3 coating is completed, place the sample in a room temperature environment of 25℃ for curing. The curing time is set to 3~5 days to ensure that the coating is fully cured and forms a stable coating.

[0118] The epoxy anti-corrosion coatings prepared in Examples 1-5 and Comparative Example 1 were subjected to mechanical property tests and anti-corrosion performance tests, respectively; the test results are shown in Tables 3-7 below.

[0119] Table 3. Hardness test results of the epoxy anticorrosion coatings prepared in Examples 1-5 and Comparative Example 1

[0120]

[0121] The data in Table 3 show that, in the comparison between Examples 1-5 and Comparative Example 1, the hardness of the coating first decreased and then increased with the increase of YG content. Examples 1 and 2 had the lowest hardness (only H), while in Example 3, the hardness recovered to 2H. This trend indicates that adding an appropriate amount of hot slag powder helps improve the hardness of the coating, but excessive addition may lead to a decrease in performance. This is mainly because zinc phosphate-based zinc phosphate particles have high hardness, can withstand external stress and transfer it to the surrounding matrix, reducing local stress concentration and thus improving the hardness of the coating. Furthermore, zinc phosphate can be uniformly dispersed in the coating, filling the pores and defects on the coating surface, reducing internal voids and forming a dense structure. As a rigid particle, the hot slag powder, while dispersed between zinc phosphate particles, fills the pores in the zinc phosphate network, achieving a synergistic reinforcing effect, thereby jointly improving the mechanical properties of the coating.

[0122] Table 4 Adhesion test results of epoxy anticorrosion coatings prepared in Examples 1-5 and Comparative Example 1

[0123]

[0124] The data in Table 4 show that the adhesion grades of Examples 1-5 are all 0, while the adhesion of the pure zinc phosphate coating (Comparative Example 1) is only 1. This indicates that the combined addition of hot slag micron powder and zinc phosphate improves the adhesion of the coating, bringing the adhesion grades of Examples 1-5 to 0. This composite enhancement mechanism mainly stems from the following two aspects: First, zinc phosphate can stably bind with the resin matrix and react with the substrate to form a dense phosphate conversion film, thus improving adhesion; second, the hot slag particles have irregular morphology and a certain roughness, which can form "anchor points" when dispersed in the coating, increasing the contact area and mechanical interlocking between the coating and the substrate; the synergistic effect of the two enhances the chemical bonding force between the substrate surface and the organic epoxy resin, thereby effectively improving the adhesion of the coating.

[0125] Table 5. Flexibility test results of the epoxy anticorrosion coatings prepared in Examples 1-5 and Comparative Example 1

[0126]

[0127] The data in Table 5 show that when the mass ratio of hot slag powder to zinc phosphate is 3:1 (Example 3), the coating flexibility is 13 mm. However, as the content of hot slag powder continues to increase, the coating flexibility begins to decrease. This is because, on the one hand, the irregular particles of hot slag powder form "anchor points" that hinder crack propagation, and zinc phosphate fills the gaps to form a dense structure. The two work together to disperse local stress when the coating is under stress, avoiding brittle fracture caused by stress concentration. On the other hand, the size difference between the two achieves gradient filling, ensuring the density of the coating and enhancing its flexibility. However, when the content of hot slag is too high, it will lead to the formation of local defects inside the coating, thus causing a decrease in the coating flexibility.

[0128] Table 6. Preparations obtained from Examples 1-5 and Comparative Example 1

[0129] Salt spray resistance test results of epoxy anti-corrosion coatings

[0130]

[0131] Depend on Figure 3 The data in Table 6 show that corrosion occurred in all cross-shaped areas of the coating after accelerated salt spray corrosion. Specifically, Comparative Example 1 showed severe corrosion at the scratched areas, accompanied by numerous bubbles; Example 1 also exhibited severe corrosion, with reduced bubble diameter and number; Examples 2, 4, and 5 all showed severe corrosion at all four scratches, but no bubbles were observed, and Example 3 showed almost no escaping corrosion, indicating the best salt spray corrosion resistance. This suggests that the composite filler formulation in Example 3 was optimal, exhibiting good dispersion uniformity in the coating without significant agglomeration, thus effectively hindering the penetration of corrosive media and improving shielding performance. In contrast, other fillers, due to uneven dispersion or poor interfacial bonding, caused localized defects, accelerating corrosion propagation. The salt spray resistance test results demonstrate that a good composite filler formulation can improve the salt spray corrosion resistance of epoxy coatings.

[0132] Depend on Figure 4 and Figure 5 By comparing the surface morphology changes of the coatings before and after immersion, the coatings' impermeability was evaluated. After 216 hours of brine immersion, it was observed that the surfaces of Examples 2-5 maintained good uniformity and structural integrity, without common defects such as blistering, rust, or cracks, demonstrating excellent impermeability and corrosion resistance, effectively blocking the penetration of corrosive media and protecting the substrate from erosion. In contrast, Comparative Example 1 and Example 1 showed pores on their surfaces, indicating that the solution damaged the surface structure of the coatings, resulting in lower impermeability. In summary, adding an appropriate amount of hot slag micro powder can fill the voids in the coating, optimize the microstructure, and improve the surface density and corrosion resistance of the coating. However, excessive addition of hot slag micro powder can easily lead to an increase in surface defects due to uneven dispersion, thus reducing the overall protective performance of the coating.

[0133] Table 7. 7-day water absorption rate test results of the epoxy anticorrosion coatings prepared in Examples 1-5 and Comparative Example 1.

[0134]

[0135] Depend on Figure 6 The data in Table 7 show that the 7-day water absorption rates of Comparative Example 1 and Examples 1-5 are 0.73 wt.%, 0.62 wt.%, 0.41 wt.%, 0.22 wt.%, 0.48 wt.%, and 0.51 wt.%, respectively, exhibiting a trend of first decreasing and then increasing. The coating of Example 3 has the lowest water absorption rate (0.22 wt.%), which corresponds to the excellent performance of Example 3 in the previous salt water immersion test, where the coating maintained a uniform and intact surface without blistering or rust, confirming its optimal water resistance and impermeability. In the system, zinc phosphate constructs a continuous physical barrier layer, significantly extending the penetration path of corrosive media such as water molecules and chloride ions, laying the foundation for the coating's barrier performance. The hot slag fills the gaps in the zinc phosphate layer, further filling the internal pores of the coating, which is also the reason for the strong salt immersion resistance of Examples 2-5. In addition, during the salt water immersion process, water diffuses through the concentration gradient inside and outside the coating until osmotic equilibrium is reached. An appropriate amount of hot slag can effectively fill the pores of the coating, improve its density, and delay moisture migration, thereby reducing water absorption and enhancing its salt immersion corrosion resistance. However, when excessive hot slag is added, its large specific surface area and hydrophilic surface characteristics easily lead to particle agglomeration, resulting in decreased local compatibility of the coating and an increase in microscopic defects. In summary, the synergistic effect of hot slag and zinc phosphate depends on a reasonable ratio, especially when the ratio of zinc phosphate to hot slag powder is 1:3, the overall anti-corrosion performance of the coating is optimal.

[0136] Depend on Figures 7-8 Analysis shows that the contact angles of Comparative Example 1 and Examples 1-5 are 69.01°, 75.27°, 78.14°, 85.56°, 76.58°, and 72.47°, respectively. With the increase of the hot slag powder content, the contact angle first increases and then decreases, with Example 3 showing the largest contact angle, indicating the best hydrophobicity. This is consistent with previous salt water immersion test results, further proving that Example 3 has the best anti-corrosion effect. In summary, this is because, on the one hand, the addition of hot slag powder can fill the internal pores of the coating, improving overall density and reducing water penetration channels; simultaneously, the rough structure of the hot slag powder surface can reduce the actual solid-liquid contact area, thereby improving hydrophobicity. On the other hand, zinc phosphate not only forms a phosphate protective film, further optimizing the microstructure of the coating surface, but also provides support for improved hydrophobicity. This test result indicates that Example 3 has the best formulation effect and can improve the anti-corrosion performance of the coating.

[0137] Depend on Figure 9It can be seen that the impedance modulus of Comparative Example 1 and Examples 1-5 at a frequency of 0.01Hz is 1.51×10⁻⁶. 4 8.91×10 4 3.39×10 5 1.55×10 7 5.20×10 5 1.26×10 6 Ω·cm 2 .

[0138] Figure 9 The formulas for calculating the horizontal and vertical coordinates are as follows:

[0139] X = lg(H);

[0140] Y = lg(R);

[0141] In the formula, X is Figure 9 The horizontal axis represents the result, where H is the current frequency and Y is the vertical axis. Figure 9 The result is shown on the vertical axis, where R is the impedance modulus.

[0142] Among them, the impedance modulus of Examples 3 and 5 is relatively high, exceeding 1.0 × 10⁻⁶. 6 Ω·cm 2 This indicates that both coatings possess excellent corrosion resistance, and the impedance modulus of Example 3 is significantly higher than that of the other coatings, indicating that its anti-corrosion performance is the best. Zinc phosphate has a limited ability to react with the substrate to form a dense phosphate conversion film. When the formulation is as in Example 3, an appropriate amount of zinc phosphate can be evenly distributed around the hot slag powder, ensuring sufficient chemical bonding sites with the substrate and forming a stable "hot slag-zinc phosphate-resin" network through chemical bonds with the hot slag and resin. Figure 3 The results of the salt spray test show that the coating porosity is reduced to a minimum, which can block the penetration of corrosive media to the greatest extent.

[0143] This invention used a three-electrode system to test the Tafel polarization curves of different coatings, such as... Figure 10 As shown, the higher the corrosion potential E of the coating, the better its anti-corrosion performance. The corrosion potentials of Comparative Example 1 and Examples 1-5 are -0.63V, -0.56V, -0.33V, -0.04V, -0.24V, and -0.39V, respectively. Figure 10 The corrosion current density (corresponding to the lowest point on the vertical axis of the TAF curve) is 5.84 × 10⁻⁶. -6 A·cm -2 8.56×10 -5 A·cm -2 4.26×10 -5 A·cm -2 2.78×10 -7 A·cm -2 6.21×10 -6 A·cm -2 and 8.93×10 -5 A·cm -2 ;

[0144] (The corrosion potential is the abscissa of the intersection of the cathodic and anodic fitted lines in the Tafe curve, and the corrosion current is the ordinate of the intersection of the cathodic and anodic fitted lines in the Tafe curve.)

[0145] The formula for calculating corrosion current density is as follows:

[0146] I corr =I / S;

[0147] In the formula I corr I represents the corrosion current density; I is the corrosion current, automatically fitted by chi660e software with a fitting range of ±0.06V; and S is the effective test area, with a size of 1cm². 2 .

[0148] Figure 10 The formulas for calculating the horizontal and vertical coordinates are as follows:

[0149] X=E corr ;

[0150] Y=lg(I corr );

[0151] In the formula, X is Figure 10 The result of the middle x-axis, E corr Y represents the corrosion potential, and Y represents the longitudinal direction. Figure 10 The result of the middle ordinate, I corr (This represents the corrosion current density.)

[0152] The results showed that the anti-corrosion performance of Examples 1-5 was superior to that of Comparative Example 1 without YG, indicating that the hot slag powder has a positive effect on improving the anti-corrosion performance of the coating. Example 3 of this invention exhibited the best overall performance, with the highest corrosion potential closest to a positive value and the lowest corrosion current density. Furthermore, the addition of zinc phosphate further enhanced the physical shielding effect of the coating, synergistically constructing a denser barrier layer with the hot slag powder, thus slowing down the rusting rate of the substrate. These test results are consistent with the salt spray test results, further demonstrating that the anti-corrosion performance of the coating is optimal when the ratio of YG to LX is 3:1.

[0153] Depend on Figure 11It can be seen that different amounts of YG hot slag micro powder added have an effect on the surface morphology of the coating. Comparative Example 1 shows a large number of obvious cracks and pores on its surface. These microscopic defects become channels for the rapid intrusion of corrosive media, directly inducing corrosion failure phenomena such as red rust and blistering in the substrate. As the content of hot slag micro powder increases, the size and number of cracks and pores in Example 1 decrease, and its surface density improves. The surface of Example 2 is even denser, with no significant pores, but still retains a small number of fine cracks, further improving the coating's density. The surface of Example 3 has no pores or microcracks, indicating that the synergistic filling of the internal voids by the hot slag micro powder and zinc phosphate at this ratio significantly improves the coating's density. In addition, obvious particle agglomeration phenomena appeared on the surfaces of Examples 4 and 5. This is because, although the coating appears dense, this phenomenon disrupts the structural continuity and integrity of the coating, thus adversely affecting the coating's mechanical properties and anti-corrosion protection effect. The SEM microstructure analysis results of this invention are consistent with the conclusion that Example 3 of the aforementioned salt spray corrosion experiment showed the best anti-corrosion performance, further confirming that the ratio of hot slag powder to zinc phosphate plays a key regulatory role in the formation of coating microstructure and corrosion protection behavior.

[0154] This invention utilizes the synergistic effect of hot-pressed slag micro-powder and zinc phosphate to significantly improve the anti-corrosion performance of epoxy coatings. Electrochemical test results show that, as Figure 10 As shown, Example 3 has the most positive corrosion potential (-0.04V) and the lowest corrosion current density (2.78×10⁻⁶). -7 A·cm -2 It exhibits excellent corrosion resistance. For example... Figure 12 As shown, zinc phosphate contains zinc phosphate tetrahydrate and zinc powder, which can fill the gaps between the zinc phosphate and the steel slag powder to achieve a "coarse-fine complementary" internal structure: First, the steel slag powder acts as the main skeleton to fill the voids in the resin matrix, while zinc phosphate fills the micro-gaps between the steel slag powder particles; Second, the tightly stacked zinc phosphate forms a dense protective layer, improving the coating's corrosion resistance and mechanical properties; Third, the irregular morphology of the steel slag powder increases the surface roughness of the coating, trapping air when in contact with liquid to form an "air cushion effect," while zinc phosphate optimizes the surface energy of the coating and improves the overall performance of the coating.

Claims

1. A two-component epoxy anti-corrosion coating for hot-pressed slag micro-powder synergistic with zinc phosphate, characterized in that, The mixture includes fillers, resin solution, and additives, and the amounts of each component by weight are as follows: 72-120 parts hot-pressed residue powder, 36 parts talc powder, 24-72 parts zinc phosphate, 120 parts epoxy resin solution, 1.5 parts wetting and dispersing stabilizer, 1.5 parts anti-settling agent, 0.3 parts leveling agent and 0.15 parts defoamer; Among them, the mixed filler composed of hot slag, talc powder and zinc phosphate accounts for 60% of the total amount of components without additives.

2. The hot-pressed slag micro-powder synergistic zinc phosphate two-component epoxy anti-corrosion coating according to claim 1, characterized in that, The particle size of the hot-cured slag powder is 800 mesh, and the hot-cured slag contains Al2O3+CaO+Fe. x O≥65%.

3. The hot-pressed slag micro-powder synergistic zinc phosphate two-component epoxy anti-corrosion coating according to claim 1, characterized in that, The zinc phosphate has a particle size of 800 mesh; the zinc phosphate minerals include: zinc phosphate tetrahydrate, zinc phosphate dihydrate, and elemental zinc.

4. The two-component epoxy anti-corrosion coating with hot-pressed slag micro-powder and zinc phosphate as described in claim 1, characterized in that, The wetting and dispersing stabilizer is a polyurethane block-modified polycarboxylic acid polymer copolymer, model XYS-6800; the anti-settling agent is a modified polyurea, obtained from polyurea-branched monoalkylamine, model 410L; the leveling agent is a polyether-modified siloxane, model XYS-5313; and the defoamer is a polyether-modified siloxane, model XYS-6550.

5. The two-component epoxy anti-corrosion coating with hot-pressed slag micro-powder and zinc phosphate as described in claim 1, characterized in that, The epoxy resin solution is prepared by mixing epoxy resin and xylene-n-butanol composite solvent at a mass ratio of 1:1, wherein the mass ratio of xylene to n-butanol is 7:

3.

6. A method for preparing a two-component epoxy anti-corrosion coating with hot-pressed slag micro-powder and zinc phosphate as described in any one of claims 1 to 5, characterized in that, The steps are as follows: S1: Place the hot-cured residue powder in a 105℃ oven for 6 hours to remove moisture, then remove and set aside. S2: Prepare an epoxy resin solution by mixing epoxy resin and xylene-n-butanol composite solvent at a mass ratio of 1:

1. Then, add the epoxy resin solution to a stirring tank and add wetting and dispersing stabilizer, anti-settling agent, leveling agent and defoamer in sequence. Stir and disperse for 15 minutes after each material is added. S3: Add talc powder, zinc phosphate and hot slag powder pretreated in S1 to the S2 mixing tank, then add glass beads and increase the speed to 1200 r / min for grinding for 4 hours. Finally, filter the mixture to obtain a two-component epoxy anti-corrosion coating of hot slag powder and zinc phosphate.

7. The preparation method of the hot-quenching slag micro-powder synergistic zinc phosphate two-component epoxy anti-corrosion coating according to claim 6, characterized in that, In step S3, during the grinding process, the fineness is measured every 30 minutes using a scraper fineness gauge. When the fineness reaches below 35 μm, the grinding process is stopped.

8. The application of the hot slag micro powder synergistic zinc phosphate two-component epoxy anti-corrosion coating according to any one of claims 1 to 5 in the anti-corrosion coating of carbon steel and tinplate metal substrates in marine engineering, petrochemical or transportation fields.

9. The application according to claim 8, characterized in that, The method is as follows: S1: Use a small sanding belt with a roughness of 250 mesh and a size of 330×10mm to perform two full grindings on the surface of the tinplate substrate. The grinding direction is the same each time and the two grinding directions are perpendicular to each other to remove surface rust products, oxide layer and impurities. S2: After polishing, wipe and clean the surface of the tinplate with anhydrous ethanol and deionized water in turn, and then let it air dry naturally for later use. S3: Use a coater to evenly apply the coating to the surface of the pretreated tinplate to form a coating with a thickness of 100μm. S4: Place the coated sample in a 25°C room temperature environment for 3-5 days to allow the coating to fully cure and form a stable anti-corrosion coating.

10. The application according to claim 9, characterized in that, The anti-corrosion coating has a hardness of 2H, an adhesion grade of 0, a flexibility of 13mm, a 7-day water absorption rate of 0.22wt.%, and an impedance modulus of 1.55×10 at a frequency of 0.01Hz. 7 Ω·cm 2 The corrosion potential is -0.04V, and the corrosion current density is 2.78×10⁻⁶. -7 A·cm -2 The contact angle is 85.56°.

Images