Iron-based amorphous alloy corrosion-resistant coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of surface treatment, and particularly relates to an iron-based amorphous alloy corrosion-resistant coating and a preparation method and application thereof. According to the coating and the preparation method thereof, the rare earth Y is introduced into the iron-based amorphous alloy (Fe65Cr14Mo5Ni5B10), so that the corrosion resistance of the coating can be further improved; meanwhile, the rare earth Y can refine the amorphous structure, and the mechanical property of the coating is further improved. According to the invention, the rare earth Y and micro-arc oxidation are cooperated to realize self-hole-sealing of the coating, and an organic coating does not need to be additionally arranged. The preparation method provided by the invention is suitable for complex curved surface workpieces (such as pump valves and propellers), the surface roughness Ra after spraying is less than 1.6 microns, and the workpieces can be directly installed for use.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment technology, specifically relating to a corrosion-resistant coating for iron-based amorphous alloys, its preparation method, and its application. Background Technology

[0002] With the gradual depletion of land resources and the increasing development of marine resources, the number of marine engineering equipment, such as offshore oil drilling platforms, offshore wind power, nuclear power, ships, and port machinery, is growing rapidly. However, the marine environment is extremely complex and harsh. Marine engineering equipment is exposed to high salinity, high humidity, wave impact, and marine organism attachment for extended periods, resulting in severe corrosion problems. This leads to rapid equipment damage and failure, shortened service life, and significantly increased maintenance costs. Therefore, there is an urgent need for high-performance seawater corrosion-resistant materials to protect marine engineering equipment.

[0003] Iron-based amorphous alloys have short-range ordered and long-range disordered atomic structures, uniform chemical composition, no component segregation or agglomeration, and no defects such as vacancies or dislocations. This reduces the probability of corrosion by corrosive media through these defects, giving them a significant advantage over crystalline alloys of the same composition in terms of seawater corrosion resistance. In addition to corrosion resistance, iron-based amorphous alloys also have high hardness, high strength, and strong friction and wear resistance, which can well meet the requirements of marine engineering equipment in complex marine environments.

[0004] However, while existing Fe-based amorphous coatings (such as SAM1651) exhibit better corrosion resistance than traditional materials, they also have limitations in high Cl- content. - There is still a risk of localized pitting corrosion in concentrated seawater (corrosion current density > 1×10⁻⁶). -8 A / cm 2 Rare earth elements (such as Y and Ce) are known to refine grains and enhance the amorphous forming ability of alloys. However, in existing technologies, excessively high rare earth additions (>5wt%) can easily lead to the precipitation of crystalline phases, which reduces corrosion resistance; while excessively low additions (<0.5wt%) cannot form an effective passivation film. In addition, traditional sealing processes often rely on organic coatings (such as epoxy resin), which have poor adhesion to the metal substrate and are easily peeled off under high pressure. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant coating for iron-based amorphous alloys, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a corrosion-resistant coating on an iron-based amorphous alloy, comprising the following steps: The raw materials corresponding to the iron-based amorphous alloy are mixed with yttrium oxide and smelted to obtain molten steel; the chemical composition of the iron-based amorphous alloy is Fe. 65 Cr 14 Mo5Ni5B 10; The molten steel is atomized to obtain a doped amorphous alloy; The iron-based amorphous alloy corrosion-resistant coating is obtained by spraying the doped amorphous alloy onto the substrate surface using supersonic flame spraying technology and then performing micro-arc oxidation.

[0007] Preferably, the mass of the yttrium oxide is 1 to 1.5% of the mass of the iron-based amorphous alloy.

[0008] Preferably, the atomization conditions include: using a protective gas as the atomizing gas and an atomization pressure of 7~9 MPa.

[0009] Preferably, before spraying, the substrate is preheated at a temperature of 90-110°C.

[0010] Preferably, the conditions for the supersonic flame spraying technology include: a spraying speed of 1200~1500m / s and a flame temperature of 1800~2000℃.

[0011] Preferably, the electrolyte used in the micro-arc oxidation is a Na2SiO3 solution, and the mass concentration of the Na2SiO3 solution is 5-6%. The voltage for the micro-arc oxidation is 300~320V.

[0012] The present invention also provides a corrosion-resistant iron-based amorphous alloy coating prepared by the preparation method described in the above technical solution.

[0013] Preferably, the thickness of the iron-based amorphous alloy corrosion-resistant coating is 100~300μm.

[0014] Preferably, the yttrium doping mass percentage in the iron-based amorphous alloy corrosion-resistant coating is 1~1.5%.

[0015] The present invention also provides the application of the iron-based amorphous alloy corrosion-resistant coating described in the above technical solution in marine engineering equipment.

[0016] This invention provides a method for preparing a corrosion-resistant coating of an iron-based amorphous alloy, comprising the following steps: mixing raw materials corresponding to the iron-based amorphous alloy with yttrium oxide, and smelting to obtain molten steel; the chemical composition of the iron-based amorphous alloy is Fe. 65 Cr 14 Mo5Ni5B 10 The molten steel is atomized to obtain a doped amorphous alloy; the doped amorphous alloy is sprayed onto the substrate surface using supersonic flame spraying technology, followed by micro-arc oxidation to obtain a corrosion-resistant coating of the iron-based amorphous alloy.

[0017] Compared with the prior art, the beneficial effects of the present invention include: (1) Breakthrough in corrosion resistance: In a 3.5% NaCl solution, the corrosion potential increased to -0.18V (vs. SCE), and the corrosion current density was as low as 2.1×10⁻⁶. -8 A / cm 2 (10 times lower than coating without added Y). No pitting corrosion after 5000h salt spray test. Applied to ship anchor chains in Qingdao waters, the coating thickness loss was <1μm after 12 months.

[0018] (2) Improved mechanical properties: Rare earth Y refines the amorphous structure, the coating hardness reaches 1100~1300HV (15% higher than the traditional Fe-based amorphous coating), the bonding strength is ≥69MPa, and the friction coefficient is reduced to 0.03.

[0019] (3) Process advantages: Yttrium oxide nanoparticles and micro-arc oxidation work together to achieve "self-sealing pores" in the coating, eliminating the need for external organic coatings and withstanding water pressure up to 3000m in the deep sea. It is suitable for complex curved workpieces (such as pumps, valves, propellers), and the surface roughness Ra after spraying is <1.6μm, which can be directly installed and used. Attached Figure Description

[0020] Figure 1 The image shows a cross-sectional SEM image of the iron-based amorphous alloy corrosion-resistant coating obtained in Example 1. Detailed Implementation

[0021] This invention provides a method for preparing a corrosion-resistant coating on an iron-based amorphous alloy, comprising the following steps: The raw materials corresponding to the iron-based amorphous alloy are mixed with yttrium oxide and smelted to obtain molten steel; the chemical composition of the iron-based amorphous alloy is Fe. 65 Cr 14 Mo5Ni5B 10 ; The molten steel is atomized to obtain a doped amorphous alloy; The doped amorphous alloy is sprayed onto the substrate surface using supersonic flame spraying technology, followed by micro-arc oxidation to obtain the corrosion-resistant coating of the iron-based amorphous alloy. This invention involves mixing raw materials corresponding to iron-based amorphous alloys with yttrium oxide and then smelting them to obtain molten steel.

[0022] In this invention, the chemical composition of the iron-based amorphous alloy is Fe. 65 Cr 14 Mo5Ni5B 10 The corresponding raw materials preferably include pure iron, ferroborone, ferromolybdenum, ferrochrome alloy, and ferronickel alloy. This invention does not impose any special limitations on the proportions of the raw materials, as long as the desired iron-based amorphous alloy with the required chemical composition can be obtained.

[0023] In this invention, the particle size D50 of the yttrium oxide is preferably 20-50 μm. In this invention, the mass of the yttrium oxide is preferably 1-1.5% of the mass of the iron-based amorphous alloy, specifically 1%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%.

[0024] The present invention does not impose any special limitations on the mixing and melting process, as long as all raw materials can be mixed evenly and completely melted.

[0025] After obtaining the molten steel, the present invention atomizes the molten steel to obtain a doped amorphous alloy.

[0026] In this invention, the preferred atomization conditions include: using a protective gas as the atomizing gas, preferably argon; and an atomization pressure of 7-9 MPa, specifically preferably 8 MPa. This invention does not impose any special limitations on the atomization process; any process well-known to those skilled in the art can be used.

[0027] In this invention, the D50 of the doped amorphous alloy is preferably 25~50μm.

[0028] After obtaining the doped amorphous alloy, the present invention uses supersonic flame spraying technology to spray the doped amorphous alloy onto the surface of the substrate and then performs micro-arc oxidation to obtain the corrosion-resistant coating of the iron-based amorphous alloy.

[0029] In this invention, the substrate is preferably 30CrMnSiA alloy steel. Before spraying, the substrate is preheated, preferably at a temperature of 90-110°C, more preferably 100°C.

[0030] In this invention, the preferred conditions for the supersonic flame spraying technology include: a spraying speed of 1200~1500 m / s, specifically 1200 m / s, 1300 m / s, 1400 m / s, or 1500 m / s; and a flame temperature of 1800~2000℃, specifically 1800℃, 1900℃, or 2000℃. In this invention, the supersonic flame spraying technology enables the formation of a highly dense coating through plastic deformation, mechanical interlocking, and rapid solidification.

[0031] In this invention, the electrolyte used for micro-arc oxidation is preferably a Na2SiO3 solution, and the mass concentration of the Na2SiO3 solution is preferably 5-6%; the voltage for micro-arc oxidation is preferably 300-320V. In this invention, using a Na2SiO3 solution as the electrolyte for micro-arc oxidation can form an amorphous SiO2 film on the surface, sealing the pores in the material and thus improving its corrosion resistance.

[0032] The present invention also provides a corrosion-resistant iron-based amorphous alloy coating prepared by the preparation method described above. In the present invention, the thickness of the corrosion-resistant iron-based amorphous alloy coating is preferably 100~300 μm; the mass percentage of yttrium doping in the corrosion-resistant iron-based amorphous alloy coating is preferably 1~1.5%.

[0033] The present invention also provides the application of the iron-based amorphous alloy corrosion-resistant coating described in the above technical solution in marine engineering equipment.

[0034] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0035] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] Example 1 According to the iron-based amorphous alloy Fe 65 Cr 14 Mo5Ni5B 10 To determine the chemical composition, weigh out the required 32.5 kg of pure iron, 5 kg of ferroborone, 2.5 kg of ferromolybdenum, 7 kg of ferrochrome alloy, 2.5 kg of ferronickel alloy, and 0.5 kg of yttrium oxide nanoparticles (particle size D50 of 40 μm) and place them into the melting furnace of the atomization equipment for melting. Turn on the melting and heating switch of the atomization equipment to melt the raw materials in the crucible. When the molten steel in the crucible reaches the atomization temperature, pour the molten steel into the atomization can for atomization and powdering. The gas used for atomization is argon. Adjust the powdering gas pressure to 8MPa to obtain a doped amorphous alloy (D50 is 40μm). The substrate (30CrMnSiA alloy steel) was preheated to 100℃; the doped amorphous alloy obtained above was added to a supersonic flame spraying device, and the supersonic flame spraying device was turned on to spray the surface of the substrate at a spraying speed of 1500m / s and a flame temperature of 1900℃. The coated substrate is placed in an electrolyte (5% Na2SiO3 solution) for micro-arc oxidation. The voltage during micro-arc oxidation is 300V, resulting in the iron-based amorphous alloy corrosion-resistant coating with a thickness of 100μm and a yttrium doping mass percentage of 1%.

[0037] Comparative Example 1 A corrosion-resistant iron-based amorphous alloy coating was prepared according to the method in Example 1, wherein no yttrium oxide was added.

[0038] Comparative Example 2 A corrosion-resistant iron-based amorphous alloy coating was prepared according to the method described in Example 1, wherein the iron-based amorphous alloy was replaced with SAM1651 (Fe 48 Mo 14 Cr 15 Y2C 15 B6).

[0039] Comparative Example 3 The iron-based amorphous alloy corrosion-resistant coating was prepared according to Example 1, with 0.4 wt% yttrium oxide nanoparticles added.

[0040] Comparative Example 4 The iron-based amorphous alloy corrosion-resistant coating was prepared according to Example 1, with 5.5 wt% yttrium oxide nanoparticles added.

[0041] Comparative Example 5 A corrosion-resistant iron-based amorphous alloy coating was prepared according to the method described in Example 1. The chemical composition of the iron-based amorphous alloy is Fe. 69 Cr 10 Mo5Ni5B 10 .

[0042] Comparative Example 6 A corrosion-resistant iron-based amorphous alloy coating was prepared according to the method described in Example 1. The chemical composition of the iron-based amorphous alloy is Fe. 74 Cr6Mo5Ni5B 10 .

[0043] Comparative Example 7 The iron-based amorphous alloy corrosion-resistant coating was prepared according to the method in Example 1, omitting the micro-arc oxidation step, and using bisphenol A type epoxy resin for sealing, with a thickness of 100 μm.

[0044] Performance testing Figure 1 This is a cross-sectional SEM image of the iron-based amorphous alloy corrosion-resistant coating obtained in Example 1. Figure 1 It can be seen that the substrate and coating have good adhesion.

[0045] The coatings obtained in the examples and comparative examples were used as samples for performance testing; the test results are shown in Table 1. Corrosion potential and corrosion current density were tested in a 3.5% NaCl solution. The coating hardness, friction coefficient, surface roughness Ra, and 5000h salt spray test were tested. The samples were placed in the Qingdao sea area for 12 months, and the coating damage on the sample surface was tested after 12 months. Table 1. Performance test results of the coatings obtained in the examples and comparative examples.

[0046] As can be seen from the table above: (1) Compared with Example 1, the data of Example 1 without the addition of rare earth element Y (Comparative Example 1) are reduced. Compared with Comparative Example 2 produced by conventional process, the performance of Example 1 is significantly improved in all aspects.

[0047] (2) If the amount of rare earth added to the coating is too high (>5wt%, Comparative Example 4), it will easily lead to the precipitation of crystalline phase, which will reduce the corrosion resistance and hardness of the coating; while if it is too low (<0.5wt%, Comparative Example 3), an effective passivation film cannot be formed, and the corrosion resistance and hardness of the coating are lower than those of Example 1. (3) Due to the reduction of chromium content in the coating material (Comparative Example 5 and Comparative Example 6), the stability of the passivation film of the coating decreased, resulting in an overall decrease in the corrosion resistance of the coating material.

[0048] (4) Compared with the traditional organic coating sealing process, the micro-arc oxidation treatment sealing process used in this invention has a lower surface porosity and stronger corrosion resistance of the coating.

[0049] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant coating on an iron-based amorphous alloy, characterized in that, Includes the following steps: The raw materials corresponding to the iron-based amorphous alloy are mixed with yttrium oxide and smelted to obtain molten steel; the chemical composition of the iron-based amorphous alloy is Fe. 65 Cr 14 Mo5Ni5B 10 ; The molten steel is atomized to obtain a doped amorphous alloy; The iron-based amorphous alloy corrosion-resistant coating is obtained by spraying the doped amorphous alloy onto the substrate surface using supersonic flame spraying technology and then performing micro-arc oxidation.

2. The preparation method according to claim 1, characterized in that, The mass of the yttrium oxide is 1 to 1.5% of the mass of the iron-based amorphous alloy.

3. The preparation method according to claim 1, characterized in that, The atomization conditions include: using a protective gas as the atomizing gas and an atomization pressure of 7~9 MPa.

4. The preparation method according to claim 1, characterized in that, Before spraying, the substrate is preheated at a temperature of 90-110°C.

5. The preparation method according to claim 1, characterized in that, The conditions for the supersonic flame spraying technology include: a spraying speed of 1200~1500m / s and a flame temperature of 1800~2000℃.

6. The preparation method according to claim 1, characterized in that, The electrolyte used in the micro-arc oxidation is a Na2SiO3 solution with a mass concentration of 5-6%. The voltage for the micro-arc oxidation is 300~320V.

7. The iron-based amorphous alloy corrosion-resistant coating prepared by the preparation method according to any one of claims 1 to 6.

8. The iron-based amorphous alloy corrosion-resistant coating according to claim 7, characterized in that, The thickness of the iron-based amorphous alloy corrosion-resistant coating is 100~300μm.

9. The iron-based amorphous alloy corrosion-resistant coating according to claim 7, characterized in that, The yttrium doping mass percentage in the iron-based amorphous alloy corrosion-resistant coating is 1~1.5%.

10. The application of the iron-based amorphous alloy corrosion-resistant coating according to any one of claims 7 to 9 in marine engineering equipment.

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