Preparation method of surface bluing film of silicon-containing FeCo-based nano-alloy

Abstract

The invention discloses a preparation method of a silicon-containing FeCo-based nano-alloy surface bluing film, which is characterized by comprising silicon segregation regulation and control, dynamic gradient oxidation, interface stress slow release layer construction and post-treatment sealing process, and the silicon segregation regulation and control adopts pulse laser to induce enrichment; the dynamic gradient oxidation comprises alkaline-acidic staged treatment. Aiming at the problems of grain coarsening and film layer defects in bluing treatment of the silicon-containing FeCo nano-alloy, breakthrough is achieved through triple mechanisms of coarsening resistance, gradient film layer design and interface stress slow release, Si segregation and oxidation are induced through laser, SiO2 nano-particles are generated, grain boundaries are pinned, and high-temperature coarsening is restrained; alkaline-acid staged oxidation is adopted, synergistic oxidation of Fe, Co and Si is achieved, and cracking of a film layer is avoided; the interface stress is optimized through magnetron sputtering and annealing, the adhesive force of an oxidation film is improved, and the silicon-containing FeCo-based nano-alloy has good corrosion resistance while the inherent performance of the silicon-containing FeCo-based nano-alloy is maintained.

Description

Technical Field

[0001] The present invention relates to a process for preparing a blued film on the surface of a silicon-containing FeCo-based nanometer alloy. In particular, aiming at the problem of grain coarsening during the high-temperature oxidation of nanocrystalline alloys, an anti-coarsening mechanism combining interface engineering and dynamic passivation regulation is proposed, belonging to the technical field of metal surface treatment. Background Art

[0002] Due to its high saturation magnetization intensity, excellent mechanical properties and high-temperature stability, the silicon-containing FeCo-based nanometer alloy is widely used in the fields of aerospace, precision instruments and electronic devices. However, the surface of the silicon-containing FeCo-based nanometer alloy is prone to oxidation failure in high-temperature or corrosive environments, and a protective oxide film needs to be formed through surface modification (such as bluing treatment). The traditional bluing process generally generates an Fe3O4 film on the metal surface through alkaline oxidation, and there are various problems. First, during high-temperature oxidation, nanograins are prone to coarsening due to high surface energy, resulting in a decline in mechanical properties. Second, the silicon element in the silicon-containing FeCo alloy is prone to segregation, hindering the continuous growth of the oxide film and thus forming local defects. Moreover, the interface between the traditional oxide film and the substrate is weakly bonded, seriously reducing the film layer performance. To address the above problems, adding second-phase particles and reducing the temperature can alleviate them to a certain extent. However, while adding second-phase particles inhibits grain boundary migration, it will introduce impurity phases and affect the material purity; although reducing the temperature can reduce grain coarsening, it will lead to insufficient oxide film thickness and poor protective performance.

[0003] Therefore, there is an urgent need for a new blued film preparation process to solve the above problems and achieve good corrosion resistance of the surface oxide film while inhibiting the coarsening of the substrate grains. Summary of the Invention

[0004] The main object of the present invention is to address the problems of grain coarsening, uneven film layer and weak interface bonding during the bluing treatment of silicon-containing FeCo nanometer alloys, and a new process combining dynamic passivation and interface regulation is proposed to achieve the synergistic optimization of structure and performance.

[0005] To achieve the above object, the present invention adopts the following technical scheme: A method for preparing a blued film on the surface of a silicon-containing FeCo-based nanometer alloy, including silicon segregation regulation, dynamic gradient oxidation, construction of an interface stress relief layer and post-treatment sealing process, wherein: the silicon segregation regulation adopts pulse laser-induced enrichment; the dynamic gradient oxidation includes alkaline-acid staged treatment.

[0006] Further, the silicon segregation regulation is specifically: a. Pulse laser treatment: Use a nanosecond laser to scan the surface, with a wavelength of 1064 nm, a pulse width of 10 ns, and an energy density of 3 J / cm 2; Induce Si enrichment, oxidize it to generate SiO2 nanoparticles, pin grain boundaries and inhibit coarsening; b. Rapid annealing: Heat up to 350 - 400 °C at a rate of 15 - 20 °C / min in a tube furnace, hold for 10 - 20 min to stabilize the distribution of Si element.

[0007] Furthermore, dynamic passivation oxidation includes: a. Primary oxidation: Oxidize in a NaOH solution (pH = 12.5, 80 °C) containing 5 - 10 wt.% NaNO2 for 15 - 25 min to generate a Fe3O4 film; b. Secondary oxidation: Transfer to a phosphoric acid solution (pH = 3.0, 60 °C) containing 0.1 - 0.2 vol.% H2O2 and oxidize for 8 - 12 min to promote the co - deposition of CoOOH and SiO2, forming a Fe3O4 - CoOOH - SiO2 composite film.

[0008] Furthermore, the construction of the interface stress relief layer is specifically as follows: a. Magnetron sputtering of CrN layer: The target is high - purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min; b. In - situ annealing: Heat up to 500 °C at a rate of 10 - 15 °C / min in a vacuum furnace, hold for 20 - 30 min to promote the chemical bonding between CrN and the oxide film and reduce the interface stress.

[0009] Furthermore, the post - treatment sealing process uses silicone sealing. After hydrolyzing KH - 550 and impregnating the oxide film, it is cured in an oven to form Si - O - Si covalent bonds between the silane molecules and SiO2, covering the micropores of the film layer.

[0010] The present invention also includes substrate pretreatment, specifically as follows: a. Ultrasonic cleaning: Ultrasonically clean the alloy with acetone, anhydrous ethanol, and deionized water in sequence for 3 min to remove surface oil stains and impurities, and dry it with nitrogen to ensure no residue on the surface; b. Surface activation: Immerse in 10% dilute sulfuric acid at room temperature for 3 - 5 min to cause selective dissolution on the alloy surface, form micron - scale pits, increase the specific surface area, and thus improve the adhesion of the subsequent oxide film.

[0011] A method for preparing a blued film on the surface of a Si - containing FeCo - based nano - alloy of the present invention is detailed as follows: S1. Substrate pretreatment: a. Ultrasonic cleaning: Ultrasonically clean the alloy with acetone, anhydrous ethanol, and deionized water in sequence for 3 min to remove surface oil stains and impurities, and dry it with nitrogen to ensure no residue on the surface; b. Surface activation: Immerse in 10% dilute sulfuric acid at room temperature for 3 - 5 min to cause selective dissolution on the alloy surface, forming micron-sized pits, increasing the specific surface area, and thus enhancing the adhesion of the subsequent oxide film.

[0012] S2. Regulation of silicon element segregation: a. Pulsed laser treatment: Scan the surface with a nanosecond laser, wavelength 1064 nm, pulse width 10 ns, energy density 3 J / cm 2 ; Induce Si enrichment, oxidize it to form SiO2 nanoparticles, pin the grain boundaries and inhibit coarsening; b. Rapid annealing: Heat up to 350 - 400 °C at a rate of 15 - 20 °C / min in a tube furnace, hold for 10 - 20 min to stabilize the distribution of Si element.

[0013] S3. Dynamic passivation oxidation: a. Primary oxidation: Oxidize in a NaOH solution (pH = 12.5, 80 °C) containing 5 - 10 wt.% NaNO2 for 15 - 25 min to form a Fe3O4 film; b. Secondary oxidation: Transfer to a phosphoric acid solution (pH = 3.0, 60 °C) containing 0.1 - 0.2 vol.% H2O2 and oxidize for 8 - 12 min to promote the co-deposition of CoOOH and SiO2, forming a Fe3O4 - CoOOH - SiO2 composite film.

[0014] S4. Interface stress relief: a. Magnetron sputtering of CrN layer: The target is high-purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min; b. In-situ annealing: Heat up to 500 °C at a rate of 10 - 15 °C / min in a vacuum furnace, hold for 20 - 30 min to promote the chemical bonding between CrN and the oxide film and reduce the interface stress.

[0015] S5. Post-treatment sealing process: Hydrolyze KH-550 with a concentration of 1 - 2 wt.% for 30 min (pH = 4.5), immerse the oxide film, and then cure in an 80 °C oven for 2 h to form Si - O - Si covalent bonds between the silane molecules and SiO2, covering the micropores of the film layer.

[0016] In view of the problems of grain coarsening and film defects in the bluing treatment of silicon-containing FeCo nanoalloys, this invention achieves a breakthrough through three mechanisms: anti-coarsening, gradient film design, and interfacial stress relief. First, through laser-induced Si segregation and oxidation, SiO2 nanoparticles are generated to pin grain boundaries and inhibit high-temperature coarsening. Second, staged alkaline-acid oxidation is used to achieve the synergistic oxidation of Fe, Co, and Si, avoiding film cracking. Finally, magnetron sputtering and annealing are used to optimize interfacial stress and improve the adhesion of the oxide film. Detailed implementation mode

[0017] The above solution will be further described below in conjunction with specific implementation examples. The preferred embodiments of the present invention are described in detail as follows: Example 1

[0018] 1. Substrate pretreatment: a. Ultrasonic cleaning: The alloy is ultrasonically cleaned with acetone, absolute ethanol, and deionized water in sequence for 3 min to remove surface oil and impurities, and then dried with nitrogen to ensure no residue on the surface. b. Surface activation: At room temperature, soak in 10% dilute sulfuric acid for 3 min to cause selective dissolution on the alloy surface, forming micron-sized pits to increase the specific surface area, thereby improving the adhesion of the subsequent oxide film.

[0019] 2. Regulation of Si element segregation: a. Pulsed laser treatment: The surface is scanned with a nanosecond laser, with a wavelength of 1064 nm, a pulse width of 10 ns, and an energy density of 3 J / cm 2 ; Induce Si enrichment to oxidize and generate SiO2 nanoparticles to pin grain boundaries and inhibit coarsening; b. Rapid annealing: Heat up to 400 °C at a rate of 15 °C / min in a tube furnace and hold for 10 min to stabilize the Si element distribution.

[0020] 3. Dynamic passivation oxidation: a. Primary oxidation: Oxidize in a NaOH solution containing 5 wt.% NaNO2 (pH = 12.5, 80 °C) for 25 min to generate a Fe3O4 film; b. Secondary oxidation: Transfer to a phosphoric acid solution containing 0.1 vol.% H2O2 (pH = 3.0, 60 °C) and oxidize for 12 min to promote the co-deposition of CoOOH and SiO2 to form a Fe3O4-CoOOH-SiO2 composite film.

[0021] 4. Interfacial stress relief: a. Magnetron sputtering of CrN layer: The target is high-purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min; b. In-situ annealing: Heat up to 500 °C at a rate of 10 °C / min in a vacuum furnace, hold for 20 min to promote the chemical bonding between CrN and the oxide film and reduce the interfacial stress.

[0022] 5. Post-treatment sealing process: Hydrolyze KH-550 with a concentration of 2 wt.% for 30 min (pH = 4.5), impregnate the oxide film, and then cure it in an oven at 80 °C for 2 h to form Si-O-Si covalent bonds between the silane molecules and SiO2, covering the micropores of the film layer. Example 2

[0023] 1. Substrate pretreatment: a. Ultrasonic cleaning: Ultrasonically clean the alloy with acetone, absolute ethanol, and deionized water in sequence for 3 min to remove surface oil stains and impurities, and dry it with nitrogen to ensure no residue on the surface. b. Surface activation: Immerse the alloy in 10% dilute sulfuric acid at room temperature for 5 min to cause selective dissolution on the alloy surface, form micron-sized pits, increase the specific surface area, and thus improve the adhesion of the subsequent oxide film.

[0024] 2. Silicon element segregation regulation: a. Pulsed laser treatment: Scan the surface with a nanosecond laser, wavelength 1064 nm, pulse width 10 ns, energy density 3 J / cm 2 ; Induce Si enrichment, oxidize it to form SiO2 nanoparticles, pin the grain boundaries and inhibit coarsening. b. Rapid annealing: Heat up to 350 °C at a rate of 20 °C / min in a tube furnace, hold for 20 min to stabilize the Si element distribution.

[0025] 3. Dynamic passivation oxidation: a. Primary oxidation: Oxidize in a NaOH solution containing 5 wt.% NaNO2 (pH = 12.5, 80 °C) for 20 min to form a Fe3O4 film. b. Secondary oxidation: Transfer to a phosphoric acid solution containing 0.1 - 0.2 vol.% H2O2 (pH = 3.0, 60 °C) and oxidize for 8 min to promote the co-deposition of CoOOH and SiO2 to form a Fe3O4-CoOOH-SiO2 composite film.

[0026] 4. Interfacial stress relief: a. Magnetron sputtering of CrN layer: The target is high-purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min. b. In-situ annealing: Heat up to 500 °C at a rate of 15 °C / min in a vacuum furnace, hold for 30 min to promote the chemical bonding between CrN and the oxide film and reduce the interfacial stress.

[0027] 5. Post-treatment Sealing Process: Hydrolyze KH-550 with a concentration of 2 wt.% for 30 min (pH = 4.5), impregnate the oxide film, and then cure it in an oven at 80 °C for 2 h to form Si-O-Si covalent bonds between silane molecules and SiO2, covering the micropores of the film layer. Example 3

[0028] 1. Substrate Pretreatment: a. Ultrasonic Cleaning: Ultrasonically clean the alloy with acetone, absolute ethanol, and deionized water in sequence for 3 min to remove surface oil stains and impurities, and dry it with nitrogen to ensure no residue on the surface. b. Surface Activation: Immerse the alloy in 10% dilute sulfuric acid at room temperature for 5 min to cause selective dissolution on the alloy surface, form micron-sized pits, increase the specific surface area, and thus improve the adhesion of the subsequent oxide film.

[0029] 2. Silicon Element Segregation Regulation: a. Pulsed Laser Treatment: Scan the surface with a nanosecond laser, wavelength 1064 nm, pulse width 10 ns, and energy density 3 J / cm 2 ; Induce Si enrichment, oxidize it to form SiO2 nanoparticles, pin the grain boundaries and inhibit coarsening. b. Rapid Annealing: Heat up to 400 °C at a rate of 15 °C / min in a tube furnace and hold for 15 min to stabilize the distribution of Si elements.

[0030] 3. Dynamic Passivation Oxidation: a. Primary Oxidation: Oxidize in a NaOH solution containing 10 wt.% NaNO2 (pH = 12.5, 80 °C) for 15 min to form a Fe3O4 film. b. Secondary Oxidation: Transfer to a phosphoric acid solution containing 0.2 vol.% H2O2 (pH = 3.0, 60 °C) and oxidize for 10 min to promote the co-deposition of CoOOH and SiO2, forming a Fe3O4-CoOOH-SiO2 composite film.

[0031] 4. Interface Stress Relief: a. Magnetron Sputtering of CrN Layer: The target is high-purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min. b. In-situ Annealing: Heat up to 500 °C at a rate of 15 °C / min in a vacuum furnace and hold for 30 min to promote the chemical bonding between CrN and the oxide film and reduce the interface stress.

[0032] 5. Post-treatment sealing process: Hydrolyze KH-550 with a concentration of 1 wt.% for 30 min (pH = 4.5). After impregnating the oxide film, cure it in an oven at 80 °C for 2 h to form Si-O-Si covalent bonds between silane molecules and SiO2, covering the micropores of the film layer.

[0033] The present invention uses 3.5 wt.% NaCl as the test solution to conduct performance tests such as salt spray test and polarization self-corrosion current on the samples in the above examples. The test results are shown in Table 1.

[0034] Table 1. Performance tests of samples in the examples Sample Salt spray test (h) <![CDATA[Polarization self-corrosion current (A / cm 2 )]]> Example 1 240 <![CDATA[3.5×10 -8 > Example 2 270 <![CDATA[3.1×10 -8 > Example 3 310 <![CDATA[2.6×10 -8 > The embodiments described in the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design idea of the present invention, various modifications and improvements made by those skilled in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention. The technical content claimed by the present invention has been fully recorded in the claims.

Claims

1. A method for preparing a blued film on the surface of a silicon-containing FeCo-based nanometer alloy, characterized in that It includes silicon segregation regulation, dynamic gradient oxidation, construction of an interfacial stress relief layer, and post-treatment sealing process, among which: silicon segregation regulation uses pulsed laser-induced enrichment; dynamic gradient oxidation includes staged alkaline-acid treatment.

2. The preparation method of the blued film on the surface of the silicon-containing FeCo-based nanometer alloy according to claim 1, characterized in that the silicon segregation regulation is specifically as follows: a. Pulsed laser treatment: Use a nanosecond laser to scan the surface, with a wavelength of 1064 nm, a pulse width of 10 ns, and an energy density of 3 J / cm 2 ; Induce Si enrichment, oxidize it to generate SiO2 nanoparticles, pin grain boundaries and inhibit coarsening; b. Rapid annealing: Heat up to 350 - 400 °C at a rate of 15 - 20 °C / min in a tube furnace, hold for 10 - 20 min to stabilize the distribution of Si element.

3. The method for preparing a blued film on the surface of a silicon-containing FeCo-based nanoalloy according to claim 2, characterized in that the dynamic passivation oxidation includes a. Primary oxidation: Oxidize for 15 - 25 min in a NaOH solution (pH = 12.5, 80 °C) containing 5 - 10 wt.% NaNO2 to form a Fe3O4 film; b. Secondary oxidation: Transfer to a phosphoric acid solution (pH = 3.0, 60 °C) containing 0.1 - 0.2 vol.% H2O2 and oxidize for 8 - 12 min to promote the co-deposition of CoOOH and SiO2 to form a Fe3O4-CoOOH-SiO2 composite film.

4. The method for preparing a blued film on the surface of a silicon-containing FeCo-based nanoalloy according to claim 3, characterized in that the construction of the interfacial stress relief layer is specifically a. Magnetron sputtering of a CrN layer: The target is high-purity Cr, the reaction gas N2 / Ar = 1:4, the sputtering power is 200 W, and the sputtering time is 2 min; b. In-situ annealing: Heat up to 500 °C at a rate of 10 - 15 °C / min in a vacuum furnace, hold for 20 - 30 min to promote the chemical bonding between CrN and the oxide film and reduce the interfacial stress.

5. The method for preparing a blued film on the surface of a silicon-containing FeCo-based nanoalloy according to claim 1, characterized in that the post-treatment sealing process uses organosilicon sealing. After hydrolyzing KH-550 and impregnating the oxide film, it is cured in an oven to form Si-O-Si covalent bonds between the silane molecules and SiO2 to cover the micropores of the film layer.

6. The method for preparing a blued film on the surface of a silicon-containing FeCo-based nanoalloy according to claim 1, characterized in that it further includes substrate pretreatment, specifically a. Ultrasonic cleaning: Ultrasonically clean the alloy successively with acetone, absolute ethanol, and deionized water for 3 min to remove surface oil stains and impurities, and dry it with nitrogen to ensure no residue on the surface; b. Surface activation: Immerse in 10% dilute sulfuric acid at room temperature for 3 - 5 min to cause selective dissolution on the alloy surface to form micron-sized pits, increase the specific surface area, and thus improve the adhesion of the subsequent oxide film.