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CN-121992335-A - Preparation method of graded porous functional coating

CN121992335ACN 121992335 ACN121992335 ACN 121992335ACN-121992335-A

Abstract

The invention discloses a preparation method of a hierarchical porous functional coating, and belongs to the technical field of high-temperature alloy surface strengthening. The method first prepares NiAlMo multiple alloy powder and sorts it into alloy powder A (< 10 μm), B (10-40 μm) and C (40-70 μm) with different particle sizes, and mixes spherical aluminum powder with specific particle size into B, C. Then sand blasting coarsening is carried out on the high-temperature alloy matrix, and then plasma spraying technology is adopted to spray the three layers of powder in sequence. And finally, activating the graded alkali liquor, namely, firstly, mild reacting with low-concentration alkali liquor to form initial micropores, and then, deeply dissolving out the aluminum pore-forming agent with high-concentration alkali liquor, so that a gradient multi-scale porous structure with gradually increased pore diameters from inside to outside is formed in the coating. The invention obviously improves the bonding strength, specific surface area and stability under high-temperature service of the coating and the matrix, and is suitable for the surface strengthening and functionalization of the high-temperature alloy component under extreme working conditions.

Inventors

  • ZHAO SHUAI
  • ZHANG NANA
  • YUAN YONGQI
  • LI LULU

Assignees

  • 江苏奇纳新材料科技有限公司

Dates

Publication Date
20260508
Application Date
20260206

Claims (9)

  1. 1. A method for preparing a graded porous functional coating, comprising the steps of: s1, preparing multi-element alloy powder, namely preparing NiAlMo or NiMoAl multi-element alloy powder, and classifying and screening to obtain three alloy powders with different particle diameters: Alloy powder a with particle size <10 μm; Alloy powder B with a particle size of 10-40 μm; Alloy powder C with a particle size of 40-70 μm. S2, sand blasting treatment, namely performing sand blasting pretreatment on the surface of the high-temperature alloy matrix, and enhancing the surface roughness and activity. S3, graded spraying, namely adopting plasma spraying equipment to sequentially spray alloy powder A, alloy powder B and alloy powder C on the surface of the substrate after sand blasting, wherein: alloy powder a as a primer layer, thickness 5-15 μm; alloy powder B as bulk layer, thickness 30-50 μm; Alloy powder C as surface layer with a thickness of 50-70 μm. S4, grading, activating and pore-forming: a) The first activation, namely adopting 3-10wt% of KOH or NaOH solution to treat for 60-80min at 30-50 ℃ and carrying out mild reaction to form initial micropores; b) And activating for the second time, namely adopting a KOH or NaOH solution with the weight percent of 20-30 percent to treat for 18-20 hours at the temperature of 60-80 ℃ to accelerate the dissolution of aluminum components, expanding pores and optimizing pore size distribution, and finally forming a gradient porous structure.
  2. 2. The method of claim 1, wherein the alloy powder A, B, C is NiAlMo or NiMoAl alloy.
  3. 3. The method of preparing a graded porous functional coating according to claim 2, wherein the alloy powders B and C are further mixed with Al powder.
  4. 4. The method of claim 3, wherein the Al powder and the alloy powder A, B, C are spherical powders.
  5. 5. The method for preparing a hierarchical porous functional coating according to claim 3, wherein the Al powder in the alloy powder B has a particle size of 30-40 μm; The grain size of Al powder in the alloy powder C is 50-60 mu m.
  6. 6. The method for preparing a hierarchical porous functional coating according to claim 3, wherein the alloy powder A comprises Ni85%, al10% and Mo5%; The alloy powder B consists of Ni80.75-83.3 wt%, al11.8-14.5 wt% and Mo4.75-4.9 wt%; the alloy powder C consists of Ni72.25-80.75 wt%, al14.5-23.5 wt% and Mo4.25-4.75 wt%.
  7. 7. The method for preparing a graded porous functional coating according to claim 1, wherein the thickness of the alloy powder A sprayed is 5-15 μm; The spraying thickness of the alloy powder B is 30-50 mu m; the spraying thickness of the alloy powder C is 50-70 mu m.
  8. 8. The method for preparing a graded porous functional coating according to claim 1, wherein the first activation condition is 30-50 ℃ for 60-80min; The second activation condition is that the temperature is 60-80 ℃ and the time is 18-20h.
  9. 9. The method of any one of claims 1 to 8, wherein the plasma spraying parameters are that the input power is 65 KW to 96KW, the argon is fed into the powder, the pressure is 0.35 MPa to 0.65MPa, and the powder feeding rate is 1 r/mi to 18r/mi.

Description

Preparation method of graded porous functional coating Technical Field The invention relates to the technical field of high-temperature alloy surface strengthening and functional coating, in particular to a preparation method of a graded porous functional coating. Background The high-temperature alloy is widely applied to the fields of aerospace, energy power, petrochemical industry and the like, and the surface performance of the high-temperature alloy directly influences the service life and the operation efficiency of equipment under extreme working conditions such as high temperature, high pressure, strong corrosion and the like. Currently, thermal spraying, electroplating, and chemical vapor deposition are common surface treatment techniques. The thermal spraying process is flexible, and the coating performance is good, so that the thermal spraying process becomes one of the mainstream technologies. However, the traditional thermal spraying coating still has the problems of low porosity, small specific surface area, insufficient surface performance and the like, and is difficult to meet the application requirements under extreme working conditions. Disclosure of Invention In order to solve the problems of single pore structure, low bonding strength, insufficient specific surface area and the like of a coating in the prior art, the invention provides a preparation method of a graded porous functional coating. Technical proposal The preparation method of the graded porous functional coating provided by the invention comprises the following steps: s1, preparing multi-element alloy powder, namely preparing NiAlMo or NiMoAl multi-element alloy powder, and classifying and screening to obtain three alloy powders with different particle diameters: Alloy powder a with particle size <10 μm; Alloy powder B with a particle size of 10-40 μm; Alloy powder C with a particle size of 40-70 μm. S2, sand blasting treatment, namely performing sand blasting pretreatment on the surface of the high-temperature alloy matrix, and enhancing the surface roughness and activity. S3, graded spraying, namely adopting plasma spraying equipment to sequentially spray alloy powder A, alloy powder B and alloy powder C on the surface of the substrate after sand blasting, wherein: alloy powder a as a primer layer, thickness 5-15 μm; alloy powder B as bulk layer, thickness 30-50 μm; Alloy powder C as surface layer with a thickness of 50-70 μm. S4, grading, activating and pore-forming: a) The first activation, namely adopting 3-10wt% of KOH or NaOH solution to treat for 60-80min at 30-50 ℃ and carrying out mild reaction to form initial micropores; b) And activating for the second time, namely adopting a KOH or NaOH solution with the weight percent of 20-30 percent to treat for 18-20 hours at the temperature of 60-80 ℃ to accelerate the dissolution of aluminum components, expanding pores and optimizing pore size distribution, and finally forming a gradient porous structure. Further, spherical Al powder with particle diameters of 30-40 mu m and 50-60 mu m are mixed into the alloy powder B and the alloy powder C respectively, so that the pore-forming effect and the structural stability are improved. Further, the plasma spraying process parameters are that the input power is 65-96KW, the powder feeding gas is argon, the pressure is 0.35-0.65MPa, and the powder feeding speed is 1-18r/min. Compared with the prior art, the invention has the beneficial effects that: The structure is stable, namely the sequential combination of spraying and activating and the design of the graded particle size ensure the interface binding force and avoid the damage of the activating process to the coating structure; pore gradient, namely forming a gradient porous structure through pore diameter design which is increased from inside to outside layer by layer, thereby being beneficial to material transmission and surface performance improvement; the specific surface area is large, the graded activation obviously improves the porosity and specific surface area of the coating, and enhances the surface performance and service stability of the high-temperature alloy under extreme working conditions. Drawings FIG. 1 is a process flow diagram of a method of making the present invention; FIG. 2 is a schematic structural diagram of the resulting graded porous coating of the present invention. Detailed Description In the description of the present invention, unless otherwise indicated, the meaning of "plurality" is two or more, and the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated