Erosion-resistant composite coating and preparation method thereof

Abstract

The preparation method comprises the following steps: S1, mixing epoxy resin and an auxiliary agent, and carrying out primary revolution and rotation centrifugal stirring and defoaming to obtain an epoxy resin mixed solution; s2, adding a surface modifier into the epoxy resin mixed solution, and carrying out secondary revolution and rotation centrifugal stirring and defoaming to obtain a liquid mixture; s3, adding SiC powder into the liquid mixture, and performing revolution and rotation centrifugal stirring and defoaming for three times to obtain paste; s4, the paste is subjected to vacuum centrifugal stirring and defoaming, and the anti-erosion composite coating is obtained. The high SiC content is matched with optimization of a revolution and rotation vacuum centrifugal stirring defoaming process in different stages, particle aggregation under conventional stirring is effectively broken, the low porosity of the composite material with the high SiC filler content is achieved, and the problems that in an epoxy anti-erosion composite coating material, the SiC filler content is low, and the erosion resistance of the coating is poor are solved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to an anti-erosion composite coating and its preparation method. Background Technology

[0002] Pump body flow components (such as impellers, volutes, and protective plates in slurry pumps, and flow channels in desulfurization slurry pumps) are in long-term contact with high-speed solid media (including sand-water flow, slag slurry, lime slurry, etc.), making them susceptible to erosion and abrasive wear, resulting in a short lifespan—conventional high-chromium alloy components have a lifespan of only 30-90 days, and even after repair with existing epoxy-based wear-resistant coatings, their service life is mostly limited to 6-12 months, which is insufficient to meet the requirements for long-term stable operation. To solve the wear problem of pump body flow components, the industry has developed various epoxy resin-based wear-resistant coating technologies. Epoxy resin, due to its excellent bonding strength, acid and alkali corrosion resistance, and moldability, has become the mainstream matrix material for wear-resistant coatings.

[0003] To improve the pump body's resistance to abrasion, existing technologies add SiC filler to epoxy resin to enhance wear resistance. However, the SiC filler content is generally low, resulting in insufficient proportion of hard phase in the coating, limited resistance to impact and abrasion, and limited ability to withstand extreme wear conditions with high sand content and large particle media. The reason why the SiC filler content cannot be increased is that high-content filler is prone to uneven dispersion, resulting in limited improvement in local wear resistance of the coating. At the same time, due to the limited coating capacity of the resin matrix, high-content filler is prone to agglomeration and porosity, resulting in insufficient coating density and poor hardness, making it difficult to resist the continuous cutting of high-hardness SiO2 particles in lime slurry.

[0004] Therefore, there is an urgent need to develop a composite coating material with high SiC filler content to achieve the performance goals of epoxy resin coatings, namely "high hard phase ratio, high density, and high erosion resistance", and to extend the service life of pump body flow components. Summary of the Invention

[0005] In view of this, this application provides an anti-erosion composite coating and its preparation method to solve the problem of how to improve the density and anti-erosion performance of the coating.

[0006] To achieve the above technical objectives, this application adopts the following technical solution: In a first aspect, this application provides a method for preparing an anti-erosion composite coating, comprising the following steps: S1. After mixing epoxy resin and additives, perform a single centrifugal stirring and degassing process to obtain an epoxy resin mixture; S2. Add a surface modifier to the epoxy resin mixture, and perform a second centrifugal stirring and degassing process to obtain a liquid mixture; S3. Add SiC powder to the liquid mixture, and perform three cycles of centrifugal stirring and degassing to obtain a paste; S4. The paste is vacuum centrifuged and stirred to remove bubbles, thus obtaining the anti-erosion composite coating.

[0007] Preferably, in step S1, the revolution speed of the centrifugal stirring and degassing process is 1000-2000 rpm, the rotation speed is 1000-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the centrifugal stirring and degassing time is 1-2 minutes, the temperature is room temperature, and the pressure is atmospheric pressure.

[0008] Preferably, in step S1, the epoxy resin is one or more of the following: bisphenol A type epoxy resin with an average epoxy value of 0.50-0.56 mol / 100g, bisphenol F type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g, and alicyclic glycidyl ether type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g.

[0009] Preferably, in step S2, the surface modifier is a silane coupling agent; the amount of surface modifier is 2-3 wt% of the epoxy resin mixture.

[0010] Preferably, in step S2, the silane coupling agent includes one or more of γ-aminopropyltriethoxysilane (KH550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), and γ-methacryloyloxypropyltrimethoxysilane (KH570).

[0011] Preferably, in step S2, the revolution speed of the secondary centrifugal stirring and degassing is 1000-2000 rpm, the rotation speed is 1000-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the secondary centrifugal stirring and degassing time is 1-2 minutes, the temperature is room temperature, and the pressure is atmospheric pressure.

[0012] Preferably, in step S3, the average particle size of the SiC powder is ≥0.5mm; the mass of the SiC powder is 80-85wt% of the anti-erosion composite coating.

[0013] Preferably, in step S3, the revolution speed of the three centrifugal stirring and degassing processes is 1800-2000 rpm, the rotation speed is 1800-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the time for the second centrifugal stirring and degassing process is 1 minute, the temperature is room temperature, and the pressure is atmospheric pressure.

[0014] Preferably, in step S4, the vacuum degree of vacuum centrifugal stirring and degassing is -0.090~-0.095MPa, the revolution speed is 1000-1500 rpm, the rotation speed is 1000-1500 rpm, and the ratio of revolution speed to rotation speed is 1:1; the degassing time of vacuum centrifugal stirring and degassing is 1-2 minutes.

[0015] Secondly, this application provides an anti-erosion composite coating.

[0016] The beneficial effects of this application are as follows: This application uses a high SiC content combined with an optimized vacuum centrifugal stirring and degassing process with different stages of rotation. The entire process is based on a commercial vacuum centrifugal degassing machine, which does not require heating or special equipment and can be carried out at room temperature (5-40℃). It effectively breaks the particle agglomeration under conventional stirring, achieves low porosity of composite materials with high SiC filler content, and solves the problem of low SiC filler content and poor erosion resistance of epoxy-based anti-erosion composite coating materials. Attached Figure Description

[0017] Figure 1 Images showing the appearance of different samples after curing; Figure 2 The results are the relative density test results of different samples after curing; Figure 3 The erosion performance of different samples after curing. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] This application provides a method for preparing an anti-erosion composite coating, comprising the following steps: S1. After mixing epoxy resin and additives, perform a single centrifugal stirring and degassing process to obtain an epoxy resin mixture; S2. Add a surface modifier to the epoxy resin mixture, and perform a second centrifugal stirring and degassing process to obtain a liquid mixture; S3. Add SiC powder to the liquid mixture, and perform three cycles of centrifugal stirring and degassing to obtain a paste; S4. The paste is vacuum centrifuged and stirred to remove bubbles, thus obtaining the anti-erosion composite coating.

[0020] The inventors discovered that existing coatings generally employ a "high-speed mechanical stirring (10-25 m / s) + room temperature / heated mixing" method, failing to incorporate the synergistic effect of vacuum and centrifugal force. This process has significant drawbacks: First, air entrained during stirring forms pores, directly reducing coating density and becoming a weak point for medium particle intrusion and localized peeling. Second, when attempting to increase the SiC filler content to over 80%, the system viscosity increases dramatically, and conventional stirring struggles to overcome interparticle agglomeration forces, easily forming SiC aggregates larger than 100 μm in diameter. This results in uneven distribution of the hard phase and prevents uniform resin coating, severely limiting the potential for increasing the hard phase content and the stability of the coating's performance. Therefore, existing stirring and mixing processes are outdated; conventional stirring cannot solve the problems of uneven dispersion and pores under high filler content, making it difficult to improve coating density, hardness, and performance stability.

[0021] This application utilizes an optimized process combining high SiC content with different stages of rotational vacuum centrifugal stirring and degassing. The entire process is based on a commercial vacuum centrifugal degassing machine, requiring no heating or special equipment and can be applied at room temperature (5-40℃). This effectively breaks up particle agglomeration under conventional stirring, achieving low porosity in composite materials with high SiC filler content. It solves the problem of low SiC filler content and poor erosion resistance in epoxy-based anti-erosion composite coating materials.

[0022] Steps S1-S4 of this application are all performed in the same commercially available vacuum centrifugal stirring and degassing machine.

[0023] In some embodiments, in step S1, the revolution speed of the centrifugal stirring and degassing process is 1000-2000 rpm, the rotation speed is 1000-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the time for the centrifugal stirring and degassing process is 1-2 minutes, the temperature is room temperature, and the pressure is atmospheric pressure.

[0024] In this embodiment, the initial stirring material is entirely liquid with low viscosity and low heat generation. Using a high-speed stirring and low-time approach improves preparation efficiency. The room temperature is 20-40 degrees Celsius; the atmospheric pressure is one standard atmosphere.

[0025] In some embodiments, in step S1, the epoxy resin is one or more of the following: bisphenol A type epoxy resin with an average epoxy value of 0.50-0.56 mol / 100g, bisphenol F type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g, and alicyclic glycidyl ether type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g.

[0026] In this embodiment, the defined epoxy resin has a high crosslinking density, which is beneficial to improve the coating ability of high SiC filler and avoid filler detachment caused by insufficient adhesion of low epoxy resin (<0.20 mol / 100g). At the same time, it is suitable for the preparation of high viscosity systems in subsequent vacuum centrifugal stirring processes.

[0027] In some embodiments, in step S2, the surface modifier is a silane coupling agent; the amount of surface modifier is 2-3 wt% of the epoxy resin mixture.

[0028] In some embodiments, in step S2, the silane coupling agent includes one or more of γ-aminopropyltriethoxysilane (KH550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), and γ-methacryloyloxypropyltrimethoxysilane (KH570).

[0029] In this embodiment, the defined silane coupling agent can form chemical bonds with the hydroxyl groups on the surface of SiC particles and the epoxy groups of epoxy resin through the active groups at both ends of the molecular chain (one end is amino, epoxy, or double bond, and the other end is ethoxy / methoxy), respectively. This solves the problem of poor compatibility between filler and resin under high SiC content, and at the same time strengthens the adhesion strength between epoxy resin and SiC and the substrate, ensuring the anti-peeling of the composite coating during use. Among them, KH550 has high amino reactivity and is suitable for room temperature curing scenarios; KH560 has a tighter cross-linking of epoxy groups with resin and is suitable for scenarios requiring high hardness; KH570's double bonds can help improve the coating toughness and are suitable for scenarios with frequent impact and grinding. Multiple models are available to meet the operating conditions of different pump body flow components.

[0030] In some embodiments, in step S2, the revolution speed of the secondary centrifugal stirring and degassing is 1000-2000 rpm, the rotation speed is 1000-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the secondary centrifugal stirring and degassing time is 1-2 minutes, the temperature is room temperature, and the pressure is atmospheric pressure.

[0031] In some embodiments, in step S3, the average particle size of the SiC powder is ≥0.5mm; the mass of the SiC powder is 80-85wt% of the anti-erosion composite coating.

[0032] In this embodiment, the SiC particle size is larger than the erosion solid particle size in most application scenarios of epoxy-based erosion-resistant composite materials, which can effectively resist media erosion. Specifically, the SiC powder is obtained by grading SiC powder with a particle size of 20-70 mesh (corresponding to a particle size of 0.220-0.9 mm) and SiC powder with a particle size of 100-200 mesh; in addition, in this embodiment, the SiC content exceeds the SiC ratio (75%) in traditional SiC / epoxy resin composite erosion materials, but too high a content will result in the resin not being able to completely coat the SiC particles, which will reduce the erosion resistance.

[0033] In some embodiments, in step S3, the revolution speed of the three centrifugal stirring degassing processes is 1800-2000 rpm, the rotation speed is 1800-2000 rpm, and the ratio of revolution speed to rotation speed is 1:1; the time for the second centrifugal stirring degassing process is 1 minute, the temperature is room temperature, and the pressure is atmospheric pressure.

[0034] In this embodiment, the high rotation speed of 1800-2000 rpm can break up the entrained air into micron-sized bubbles, reducing the viscosity of the high SiC (80-85%) system through the "dilution effect" and "bubble lubrication". At the same time, the strong shear force quickly breaks up the initial agglomeration of SiC. The low time control of 1 minute can reduce the total amount of air entrained, avoid excessive bubbles from increasing the burden of subsequent degassing, and keep the system temperature ≤38℃ for a short time, which will not cause premature cross-linking of the resin, thus preserving good material flowability for subsequent vacuum degassing.

[0035] In some embodiments, in step S4, the vacuum degree of vacuum centrifugal stirring degassing is -0.090~-0.095MPa, the revolution speed is 1000-1500 rpm, the rotation speed is 1000-1500 rpm, and the ratio of revolution speed to rotation speed is 1:1; the degassing time of vacuum centrifugal stirring degassing is 1-2 minutes.

[0036] In this embodiment, the vacuum centrifugal stirring and degassing step can be performed multiple times, but it is necessary to ensure that the material temperature after each mixing is below 50°C. The degassing effect is supplemented by intermittent operation, and the temperature is controlled at ≤50°C throughout the process to further ensure process stability and avoid the entire batch of material being scrapped due to overheating. After degassing, the material should be in a dense state with no visible bubbles and SiC particles uniformly dispersed.

[0037] In this application, the vacuum level in step S4 has a greater impact than the rotational speed. The high vacuum environment of this embodiment can significantly reduce the internal pressure of bubbles, driving them to expand and escape rapidly. Even at a moderately low rotational speed of 1000-1500 rpm, micron-sized bubbles are efficiently removed through a combination of vacuum negative pressure and moderate centrifugation. The rotational speed range of 1000-1500 rpm can significantly reduce the heat generated by high-speed shearing, avoiding the material temperature from exceeding 50°C, which could lead to resin pre-curing or a sudden increase in viscosity. At the same time, it reduces the risk of SiC particles settling and stratifying due to high centrifugal force, balancing degassing efficiency and component uniformity. The 1-2 minute single degassing time avoids the cumulative heat generated during long-term processing.

[0038] This application provides an anti-erosion composite coating.

[0039] The following specific embodiments further illustrate this solution.

[0040] Example 1 A method for preparing an erosion-resistant composite coating includes the following steps: S1. Prepare epoxy resin raw materials by mixing epoxy resin (epoxy resin E51), curing agent (polyetheramine D230), diluent (epoxypropane phenyl ether), and accelerator (2,4,6-tris(dimethylaminomethyl)phenol) in a mass ratio of 100:33:10:3.3. Place the mixture in a vacuum centrifugal mixer and stir until homogeneous under normal pressure. The revolution speed and rotation speed are both 2000 rpm, and the stirring time is 1 min to obtain an epoxy resin mixture. S2. Add silane coupling agent KH550 to the epoxy resin mixture at a dosage of 2% of the mass of the epoxy resin mixture. Mix evenly under normal pressure, with both the revolution speed and the rotation speed at 2000 rpm and the stirring time at 1 min to obtain a uniformly mixed liquid mixture containing surface modifier. S3. Add SiC powder to the liquid mixture. The particle size of the SiC powder is 30-70 mesh. The SiC powder content accounts for 81.1% of the mass of the anti-erosion composite coating. Mix it in a centrifugal mixer under normal pressure. The revolution speed and rotation speed are both 2000 rpm. The stirring time is 1 min to obtain a paste. S4. Continue to vacuum and centrifuge the paste on the same vacuum centrifugal mixer to remove bubbles. The vacuum degree is controlled at -0.090MPa, the stirring speed is 1000 rpm, and the degassing time is 2 minutes to obtain the anti-erosion composite coating.

[0041] Example 2 A method for preparing an anti-erosion composite coating is the same as in Example 1, except that the SiC powder content accounts for 84.2% of the mass of the anti-erosion composite coating.

[0042] Comparative Example 1 A method for preparing an anti-erosion composite coating is the same as in Example 1, except that the SiC powder content accounts for 77.8% of the mass of the anti-erosion composite coating.

[0043] Comparative Example 2 A method for preparing an anti-erosion composite coating is the same as in Example 1, except that the SiC powder content accounts for 87% of the mass of the anti-erosion composite coating.

[0044] Testing and Evaluation Comparing the appearance of the slurries in Examples 1-2 and Comparative Examples 1-2: The prepared slurries were placed in a constant temperature drying oven and heated to 80°C for 6 hours to cure, resulting in the following appearance. Figure 1 The cured appearance shown is largely preserved after stirring. It can be seen that Comparative Example 2 exhibits obvious cracks, indicating that the excessive SiC filler content makes it difficult for the liquid resin to completely encapsulate the solid SiC particles, resulting in high viscosity that is detrimental to construction. The other three samples, however, appear as a uniformly mixed slurry.

[0045] The apparent densities of Examples 1-2 and Comparative Examples 1-2 were tested using the Archimedes' displacement method, and their relative densities (the ratio of apparent density to theoretical density) were calculated. The relative densities are as follows: Figure 2 As shown, it is evident that the relative density of Comparative Example 2 is relatively low, which is consistent with its morphology after curing. The relative densities of the other three samples are all above 98%, demonstrating the feasibility of the technology presented in this application and achieving the initial goal of high density in epoxy resin-based erosion-resistant materials with high silicon carbide content at high silicon carbide filler content.

[0046] Further erosion performance tests were conducted on Examples 1-2 and Comparative Examples 1-2. A self-made water-bearing sandblasting erosion testing machine was used, with 48-80 mesh quartz sand as the erosion particles. The sand content of the jet was approximately 25 wt%, simulating the liquid-solid two-phase erosion environment of a pump environment. The samples for the erosion test were disc-shaped samples processed by a precision surface grinder. The erosion conditions were a 30-degree angle, a time of 30 minutes, and a flow velocity of approximately 15 m / s. Figure 3 As shown, the erosion weight loss of Examples 1 and 2 is significantly lower than that of Comparative Example 1, indicating improved erosion resistance, which is significantly better than that of conventional epoxy-based erosion-resistant materials. Although the erosion resistance of Comparative Example 2 also meets the requirements of epoxy resin-based erosion-resistant composite materials, its density requirement is not met, and the high content causes problems such as high viscosity and difficult construction.

[0047] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an erosion-resistant composite coating, characterized by, The method comprises the following steps: S1. After mixing the epoxy resin and the auxiliary agent, perform primary centrifugal stirring and debubbling to obtain an epoxy resin mixture; S2. Add a surface modifier to the epoxy resin mixture and perform secondary centrifugal stirring and debubbling to obtain a liquid mixture; S3. Add SiC powder to the liquid mixture and perform tertiary centrifugal stirring and debubbling to obtain a paste; S4. Perform vacuum centrifugal stirring and debubbling on the paste to obtain the anti-erosion composite coating.

2. The method of claim 1, wherein the anti-erosion composite coating is prepared by a process comprising: In step S1, the primary centrifugal stirring and debubbling is performed at a revolution speed of 1000-2000 rpm and a rotation speed of 1000-2000 rpm, the ratio of the revolution speed to the rotation speed being 1:1, the time being 1-2 minutes, the temperature being room temperature, and the pressure being normal pressure.

3. The method of claim 1, wherein the anti-erosion composite coating is prepared by a process comprising: In step S1, the epoxy resin is one or more of bisphenol A type epoxy resin with an average epoxy value of 0.50-0.56 mol / 100g, bisphenol F type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g, and alicyclic glycidyl ether type epoxy resin with an average epoxy value of 0.20-0.56 mol / 100g.

4. The method of claim 1, wherein the anti-erosion composite coating is prepared by a process comprising: In step S2, the surface modifier is a silane coupling agent, and the amount of the surface modifier is 2-3wt% of the epoxy resin mixture.

5. The method of claim 4, wherein the anti-erosion composite coating is prepared by, In step S2, the silane coupling agent includes one or more of γ-aminopropyl triethoxysilane (KH550), γ-(2,3-epoxypropoxy) propyl trimethoxysilane (KH560), and γ-methacryloyloxypropyl trimethoxysilane (KH570).

6. The method of claim 1, wherein the anti-erosion composite coating is prepared by, In step S2, the secondary centrifugal stirring and debubbling is performed at a revolution speed of 1000-2000 rpm and a rotation speed of 1000-2000 rpm, the ratio of the revolution speed to the rotation speed being 1:1, the time being 1-2 minutes, the temperature being room temperature, and the pressure being normal pressure.

7. The method of claim 1, wherein the anti-erosion composite coating is prepared by a process comprising: In step S3, the SiC powder has an average particle size of ≥0.5mm, and the mass of the SiC powder is 80-85wt% of the anti-erosion composite coating.

8. The method of claim 1, wherein the anti-erosion composite coating is prepared by, In step S3, the tertiary centrifugal stirring and debubbling is performed at a revolution speed of 1800-2000 rpm and a rotation speed of 1800-2000 rpm, the ratio of the revolution speed to the rotation speed being 1:1, the time being 1 minute, the temperature being room temperature, and the pressure being normal pressure.

9. The method of claim 1, wherein the anti-erosion composite coating is prepared by, In step S4, the vacuum centrifugal stirring and debubbling is performed at a vacuum degree of -0.090~-0.095MPa, a revolution speed of 1000-1500 rpm, and a rotation speed of 1000-1500 rpm, the ratio of the revolution speed to the rotation speed being 1:1, and the time being 1-2 minutes.

10. The anti-erosion composite coating prepared by the method of any one of claims 1-9.

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