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CN-121976275-A - Preparation method of micro-arc oxidation electrolyte and Ce-MOF super-hydrophobic composite coating

CN121976275ACN 121976275 ACN121976275 ACN 121976275ACN-121976275-A

Abstract

The invention relates to the technical field of surface treatment engineering, in particular to a micro-arc oxidation electrolyte and a preparation method of a Ce-MOF super-hydrophobic composite coating. The micro-arc oxidation electrolyte provided by the invention comprises 8-12 g/L of sodium silicate, 6-10 g/L of sodium hydroxide, 3-7 g/L of potassium fluoride and 1-5 g/L of modified cerium oxide nano particles, can be used as a nucleation core in a micro-arc oxidation process by introducing the modified cerium oxide nano particles into the micro-arc oxidation electrolyte, is beneficial to refining the microstructure of a ceramic layer, can also be used for effectively filling micropores and channels formed by discharge, so that the porosity of a coating is remarkable and the compactness is improved, and the preparation of a super-hydrophobic composite coating shows typical super-hydrophobic characteristics through the synergistic effect of micro-arc oxidation and electrodeposition, has an excellent physical barrier function, and greatly improves the surface protection capability of rare earth magnesium alloy.

Inventors

  • LIU YAFEI
  • ZENG YUANSONG
  • XU YANJIN
  • WANG TONGMIN
  • GUO ENYU
  • KANG HUIJUN
  • CHEN ZONGNING

Assignees

  • 中国航空制造技术研究院

Dates

Publication Date
20260505
Application Date
20251217

Claims (10)

  1. 1. The micro-arc oxidation electrolyte is characterized by comprising 8-12 g/L of sodium silicate, 6-10 g/L of sodium hydroxide, 3-7 g/L of potassium fluoride and 1-5 g/L of modified cerium oxide nano particles.
  2. 2. The micro-arc oxidation electrolyte according to claim 1, comprising 9.5-10.5 g/L sodium silicate, 7.5-8.5 g/L sodium hydroxide, 4.5-5.5 g/L potassium fluoride and 1-5 g/L modified cerium oxide nanoparticles.
  3. 3. The micro-arc oxidation electrolyte according to claim 1, wherein the modified cerium oxide nanoparticles are prepared by treating cerium oxide nanoparticles with a silane coupling agent and glycerin, and the mass ratio of the cerium oxide nanoparticles to the silane coupling agent is 1:0.05-0.1.
  4. 4. The micro-arc oxidation electrolyte according to claim 1, wherein the sodium silicate, sodium hydroxide, potassium fluoride, modified cerium oxide nanoparticles and deionized water are mixed when the micro-arc oxidation electrolyte is prepared, and the particle size of the modified cerium oxide nanoparticles is 20-120 nm.
  5. 5. A micro-arc oxidation composite coating, which is characterized in that the micro-arc oxidation composite coating is prepared by micro-arc oxidation treatment by using the micro-arc oxidation electrolyte as set forth in any one of claims 1-4.
  6. 6. A method for preparing a Ce-MOF superhydrophobic composite coating based on the micro-arc oxidation electrolyte according to any one of claims 1-4, comprising the steps of: s1, preprocessing a rare earth magnesium alloy workpiece to obtain a preprocessed workpiece; s2, placing the pretreated workpiece in the micro-arc oxidation electrolyte for micro-arc oxidation treatment to obtain a rare earth magnesium alloy workpiece with a micro-arc oxidation composite coating on the surface; S3, carrying out electrodeposition treatment on the rare earth magnesium alloy containing the micro-arc oxidation composite coating by electrodepositing Ce-MOF electrolyte to obtain a rare earth magnesium alloy workpiece with a micro-arc oxidation composite film layer with the Ce-MOF coating on the surface; S4, placing the treated workpiece in the stearic acid ethanol modifier for super-hydrophobic modification to obtain the Ce-MOF super-hydrophobic composite coating with the synergistic effect of micro-arc oxidation and electrodeposition.
  7. 7. The method for preparing the Ce-MOF superhydrophobic composite coating according to claim 6, wherein in the step S1, the pretreatment comprises polishing, cleaning, alkaline cleaning and drying, wherein a constant voltage mode is adopted in the micro arc oxidation treatment, the alternating current is 250-400V, the pulse frequency is 400-500 Hz, the oxidation time is 3-5 min, the duty ratio is 3-10%, and the oxidation temperature is 20-42 ℃; Or a constant-current mode is adopted in the micro-arc oxidation treatment, wherein the direct current is 0.3-0.6A/dm < 2 >, the pulse frequency is 400-500 Hz, the duty ratio is 3-10%, the oxidation time is 3-5 min, and the oxidation temperature is 20-42 ℃.
  8. 8. The method for preparing a Ce-MOF superhydrophobic composite coating according to claim 6, wherein in step S2, the time of the micro-arc oxidation treatment is 3-10 min, and the thickness of the micro-arc oxidation composite coating is 10-50 μm.
  9. 9. The method for preparing the Ce-MOF super hydrophobic composite coating according to claim 6, wherein, In the step S3, the electrodeposited Ce-MOF electrolyte comprises 1 g-5 g of cerium nitrate hexahydrate, 1 g-5 g of trimellitic acid and N, N-dimethylformamide, wherein the electrodeposited Ce-MOF has the electrical parameters of a direct current power supply constant voltage mode and a voltage of 10-40V, the electrodeposited Ce-MOF adopts a double-electrode mode, wherein the cathode is a micro arc oxidation sample, and the electrodepositing time is 5-40 min.
  10. 10. The method for preparing a Ce-MOF super-hydrophobic composite coating according to claim 6, wherein the modifier is a stearic acid solution dissolved in absolute ethyl alcohol, wherein the stearic acid is 1-5 g, the absolute ethyl alcohol solution is 30-60 ml, and the Ce-MOF super-hydrophobic composite coating with the synergistic effect of micro-arc oxidation and electrodeposition is dried after the super-hydrophobic modification treatment is completed.

Description

Preparation method of micro-arc oxidation electrolyte and Ce-MOF super-hydrophobic composite coating Technical Field The invention relates to the technical field of surface treatment engineering, in particular to a micro-arc oxidation electrolyte and a preparation method of a Ce-MOF super-hydrophobic composite coating. Background The magnesium alloy has the advantages of low density and high specific strength, is an ideal structural material in the fields of aerospace and automobile traffic, and can obviously improve the strength and heat resistance of the magnesium alloy by introducing rare earth elements, so that the service life of the magnesium alloy in extreme environments is prolonged. However, magnesium alloy has relatively active chemical properties, and an oxide film naturally formed on the surface of the magnesium alloy is usually loose and porous and has poor compactness, so that the magnesium alloy has limited protective performance and insufficient corrosion resistance, and the wider application of the magnesium alloy is restricted to a certain extent. The magnesium alloy surface modification treatment process is a relatively effective method for improving the corrosion resistance of the material at present, and the existing surface treatment process comprises micro-arc oxidation, magnetron sputtering, electrodeposition, chemical conversion coating and the like. The micro-arc oxidation (MAO) technology is used as a high-efficiency, simple-process and environment-friendly surface treatment method, and a high-quality ceramic film layer which is firmly combined with a matrix and has a compact structure can be constructed in situ on the surface of the alloy. Meanwhile, the ceramic film layer has the characteristics of good wear resistance, corrosion resistance, high-temperature impact resistance, electric insulation and the like, so that the ceramic film layer is paid attention to in the field of magnesium alloy corrosion protection. At present, the micro-arc oxidation film layer is widely applied to corrosion protection of rare earth magnesium alloy. However, the ceramic membrane prepared by the prior micro-arc oxidation technology still has the problems that (1) the porosity is high, micropores and microcracks are easy to generate in the ceramic layer due to the high-voltage discharge effect in the micro-arc oxidation process, the porosity of the membrane layer under the traditional silicate electrolyte system is generally between 8% and 15%, corrosive medium can infiltrate into a matrix along the micropores, the protection effect is reduced, and in conclusion, the prior micro-arc oxidation technology still generally has the problems of high porosity of the membrane layer, weak interface bonding and the like in the aspect of preparing the rare earth magnesium alloy protection coating, so that the industrial application of the rare earth magnesium alloy protection coating under the high-performance requirement scene is restricted. The superhydrophobic coating can effectively solve the defects due to the unique water-repellent performance. The technology for preparing the super-hydrophobic coating on the micro-arc oxidation surface is a development trend of the coating in the related field. In recent years, MOF materials (metal organic framework materials) have been a rapidly developing coordination polymer in the last decade, showing potential in the field of superhydrophobic coatings due to their porous structure and tunable surface properties. The prior method requires a complex pretreatment process, and the bonding of the MOF and the bottom of the substrate mainly depends on physical action, so that the bonding strength is limited. Disclosure of Invention Aiming at the problems, the invention adopts the following technical scheme: In the first aspect, the micro-arc oxidation composite coating is optimized, and the micro-arc oxidation electrolyte comprises 8-12 g/L sodium silicate, 6-10 g/L sodium hydroxide, 3-7 g/L potassium fluoride and 1-5 g/L modified cerium oxide nano particles. According to the invention, modified cerium oxide nano particles are introduced into the micro-arc oxidation electrolyte, the modified cerium oxide nano particles can be used as nucleation cores in the micro-arc oxidation process, so that the micro-structure of a ceramic layer can be thinned, micropores and channels formed by discharge can be effectively filled, the porosity of a coating is remarkable, the compactness is improved, sodium silicate and sodium hydroxide together form a stable alkaline silicate base system, a necessary environment base is provided for micro-arc oxidation reaction, the conductivity of the system is enhanced by adding potassium fluoride, and F - ions contained in the potassium fluoride can react with a magnesium alloy base to form an initial fluoride transition layer, so that the binding force of a film base is effectively enhanced. Preferably, the micro-arc oxidation electrolyte comprise