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CN-121975375-A - Super-hydrophobic drag reduction composite coating based on modified ZIF-8, preparation method thereof and coated aluminum mesh

CN121975375ACN 121975375 ACN121975375 ACN 121975375ACN-121975375-A

Abstract

The invention discloses a modified ZIF-8-based superhydrophobic drag reduction composite coating, a preparation method thereof and a coated aluminum net, wherein the ZIF-8 particles are subjected to unique hydroxylation pretreatment and composite silane grafting modification, so that the ZIF-8 particles are integrated with a physical roughness construction function and a chemical hydrophobic/lubricating function, are compounded as core fillers with fluorocarbon resin and PTFE/graphite drag reduction auxiliary agents, and a stable and uniform micro-nano composite structure coating is constructed on the surface of the aluminum net by optimizing a dispersion process and spraying curing parameters. The coating synchronously realizes superhydrophobicity (the water contact angle is more than or equal to 155 degrees, the rolling angle is less than or equal to 8 degrees) and the fluid drag reduction rate is more than or equal to 25 percent, has strong mechanical stability, corrosion resistance and strong adhesive force, solves the technical bottlenecks of single function and poor durability of the traditional coating, and has simple and convenient process.

Inventors

  • GAO YUAN
  • ZHANG WENJUAN
  • WANG WEI

Assignees

  • 西安建筑科技大学

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. A super-hydrophobic drag reduction composite coating based on modified ZIF-8 is characterized in that the raw materials of the super-hydrophobic drag reduction composite coating comprise matrix resin, drag reduction auxiliary agent, hydrophobic auxiliary agent, composite solvent and modified ZIF-8 particles serving as core functional fillers, wherein the modified ZIF-8 particles are ZIF-8 particles grafted with the hydrophobic auxiliary agent after surface hydroxylation pretreatment.
  2. 2. The super-hydrophobic drag-reducing composite coating based on the modified ZIF-8 is characterized by comprising, by mass, 8-20% of modified ZIF-8 particles, 25-45% of matrix resin, 3-10% of drag-reducing auxiliary agent, 4-12% of hydrophobic auxiliary agent and 25-50% of composite solvent.
  3. 3. The modified ZIF-8-based superhydrophobic drag reduction composite coating according to claim 1 or 2, wherein the particle size of the modified ZIF-8 particles is 500 nm-3 μm, and the hydroxyl content of the surfaces of the ZIF-8 particles is 3.2-5.6 mmol/g before grafting of the hydrophobic auxiliary agent.
  4. 4. The modified ZIF-8-based superhydrophobic drag reduction composite coating as claimed in claim 1 or 2, wherein the matrix resin is selected from one or more of fluorocarbon resin, polysiloxane resin and polyurethane modified organic silicon resin, the drag reduction auxiliary agent is polytetrafluoroethylene micropowder and/or graphite micropowder, and the hydrophobic auxiliary agent is selected from one or more of perfluorodecyl triethoxysilane, heptadecafluorodecyl trimethoxysilane and octadecyltrimethoxysilane.
  5. 5. A method of preparing a modified ZIF-8 superhydrophobic drag-reducing composite coating according to any of claims 1-4, the method comprising the steps of: (1) Preparing modified ZIF-8 particles, namely carrying out hydroxylation pretreatment on ZIF-8 powder to obtain hydroxylated ZIF-8, and carrying out grafting reaction on the hydroxylated ZIF-8 and a hydrophobic auxiliary agent under a catalytic condition to obtain the modified ZIF-8 particles; (2) The preparation method comprises the steps of preparing coating slurry, namely dissolving matrix resin in part of a composite solvent to obtain a resin solution, adding the modified ZIF-8 particles and the drag reduction auxiliary agent obtained in the step (1) into the resin solution, performing dispersion treatment to obtain uniformly dispersed slurry, and adjusting the viscosity and the solid content of the slurry to obtain the coating slurry.
  6. 6. The preparation method of the modified ZIF-8-based superhydrophobic drag reduction composite coating is characterized in that in the step (1), ZIF-8 powder is added into 10-15% hydrogen peroxide solution by mass fraction, stirring is carried out for 4-8 hours at 60-75 ℃, and the grafting reaction is carried out by dispersing the hydroxylated ZIF-8 in absolute ethyl alcohol, adding a hydrophobic auxiliary agent accounting for 15-40% of the mass of the hydroxylated ZIF-8, using hydrochloric acid as a catalyst, and stirring and reacting for 8-16 hours at 55-70 ℃.
  7. 7. The preparation method of the modified ZIF-8 superhydrophobic drag reduction composite coating according to claim 5, wherein in the step (2), the dispersion treatment comprises high-speed dispersion at 3500-6000 r/min for 1.5-3 hours, and then ultrasonic dispersion with power of 300-500W for 45-90 minutes, wherein the ultrasonic dispersion is performed in an intermittent mode.
  8. 8. A super-hydrophobic drag-reduction coating aluminum net is characterized in that the super-hydrophobic drag-reduction coating aluminum net is provided with a coating formed by the super-hydrophobic drag-reduction composite coating according to any one of claims 1-4 on the surface of an aluminum net substrate, the thickness of the coating is 80-250 μm, and the surface water contact angle is more than or equal to 155 degrees and the rolling angle is less than or equal to 8 degrees.
  9. 9. The superhydrophobic drag-reducing coated aluminum net of claim 8, wherein the drag reduction rate of the coated aluminum net relative to the uncoated aluminum net is greater than or equal to 25% at 25 ℃ and water flow rate of 1 m/s; and/or after 50 times of sand paper friction under 200g load, the surface water contact angle is more than or equal to 145 degrees, and the drag reduction rate is more than or equal to 25 percent; and/or after being tested by 2.5% NaCl salt fog for 72 hours, the coating has no bubbling and falling off, and the water contact angle is more than or equal to 150 degrees; And/or, the adhesive force grade is less than or equal to grade 1 according to the GB/T9286-1998 standard.
  10. 10. A method of preparing the superhydrophobic drag-reducing coated aluminum mesh of claims 8 or 9, the method steps comprising: (a) Pretreating an aluminum net, namely degreasing, cleaning and drying the aluminum net; (b) Coating construction, namely spraying the coating slurry prepared by the method of any one of claims 5-7 on the surface of the pretreated aluminum mesh in an air spraying mode, and obtaining the super-hydrophobic drag-reduction coating aluminum mesh after pre-baking and curing.

Description

Super-hydrophobic drag reduction composite coating based on modified ZIF-8, preparation method thereof and coated aluminum mesh Technical Field The invention belongs to the technical field of functional materials and surface engineering, and particularly relates to a modified ZIF-8-based superhydrophobic drag reduction composite coating, a preparation method thereof and a coated aluminum mesh. Background The super-hydrophobic coating has great application potential in the fields of self-cleaning, anti-icing, anti-corrosion and the like due to the unique lotus leaf effect. Meanwhile, in the scenes of fluid conveying pipelines, ship shells, underwater vehicles and the like, the friction resistance between the fluid and the solid surface is reduced, and the method has remarkable significance in improving the energy efficiency and reducing the running cost. The combination of superhydrophobicity and drag reduction performance can theoretically produce a synergistic effect that the gas cushion layer (Cassie-Baxter state) formed by the superhydrophobic surface can effectively reduce the solid-liquid contact area, thereby reducing the viscous drag. Aluminum mesh is a lightweight, high strength, porous and easily formed metal substrate that has found wide application in filtration, separation, protection and fluid devices. The coating with superhydrophobic and drag reduction functions is constructed on the surface of the coating, so that the application value of the coating can be further expanded. However, most of the research in the prior art on the development of such functional coatings has focused on single superhydrophobic or drag reducing properties. While conventional superhydrophobic coatings often lack a microstructure optimized for fluid dynamics, resulting in limited drag reduction rates (typically less than 20%), single drag reduction coatings are susceptible to contamination, wetting, and loss of drag reduction in complex fluid environments. In addition, the zeolite imidazole ester framework material (ZIFs), particularly ZIF-8, has a regular porous structure, a high specific surface area and an adjustable morphology, and is an ideal candidate for constructing a micro-nano coarse structure. However, the original ZIF-8 particles have high surface chemical inertness, poor dispersibility in a polymer matrix, easy agglomeration, difficult regulation of surface energy, and difficulty in simultaneously endowing the coating with excellent hydrophobicity and specific drag reduction function. And aluminum mesh surface is smooth and is easy to form an oxide layer, so that the coating has weak adhesive force. When the coating is subjected to fluid shear, mechanical abrasion (such as sand washing) and salt spray corrosion in marine environment, the micro-nano structure and the low surface energy chemical layer of the coating are easy to damage, the performance is rapidly attenuated, and long-term use requirements are difficult to meet. In addition, the preparation of some high-performance coatings depends on complex processes such as chemical vapor deposition, electrostatic spinning and the like, and has high cost, so that uniform and large-scale coating on large-size or complex-shape aluminum mesh substrates is difficult to realize. Therefore, aiming at the technical defects of poor function cooperativity, limited application of key filler, insufficient durability of the coating and complex preparation process or low compatibility, the design and development of a super-hydrophobic drag reduction composite coating based on modified ZIF-8, a preparation method thereof and a coated aluminum net are urgently needed. Disclosure of Invention In order to overcome the defects and difficulties in the prior art, the first aim of the invention is to provide a super-hydrophobic drag reduction composite coating based on modified ZIF-8, the second aim of the invention is to provide a preparation method of the super-hydrophobic drag reduction composite coating based on modified ZIF-8, the third aim of the invention is to provide a super-hydrophobic drag reduction coating aluminum net, and the fourth aim of the invention is to provide a preparation method of the super-hydrophobic drag reduction coating aluminum net. The first aim of the invention is realized in that the super-hydrophobic drag reduction composite coating raw material comprises matrix resin, drag reduction auxiliary agent, hydrophobic auxiliary agent, composite solvent and modified ZIF-8 particles serving as core functional filler, wherein the modified ZIF-8 particles are ZIF-8 particles grafted with the hydrophobic auxiliary agent after surface hydroxylation pretreatment. The second object of the invention is achieved in that the method comprises the steps of: (1) Preparing modified ZIF-8 particles, namely carrying out hydroxylation pretreatment on ZIF-8 powder to obtain hydroxylated ZIF-8, and carrying out grafting reaction on the hydroxylated ZIF-8 and a hydrop