Preparation method and application method of aluminum-based super-corrosion-resistant coating

Abstract

The invention discloses a method for preparing an amorphous aluminum-based coating through electric arc spraying and laser remelting and the obtained coating, and belongs to the technical field of material surface engineering. The method comprises the following steps: firstly, preparing a cored wire which takes pure aluminum as a sheath and is internally filled with specific alloy powder consisting of Al, AlNi, Mg, Ti, rare earth elements and the like; then preparing an amorphous aluminum-based coating on the surface of the matrix under the optimized process parameters by adopting high-speed electric arc spraying equipment; and finally, the coating is subjected to scanning treatment through a laser remelting technology, so that pores are eliminated, the structure is improved, and a compact amorphous / nanocrystalline composite structure is formed. Through material design and composite process innovation, the problems that a traditional electric arc spraying coating is high in porosity and insufficient in bonding strength and an amorphous phase is difficult to prepare are successfully solved, the obtained coating has extremely high hardness and excellent wear resistance and corrosion resistance, the process cost is low, efficiency is high, and the method is suitable for large-scale industrial production and has wide application prospects. The method has wide application prospects in the fields of equipment remanufacturing, marine corrosion prevention, aerospace and the like.

Description

Technical Field

[0001] This invention relates to the field of materials surface engineering technology, and in particular to a method for preparing high-performance amorphous aluminum-based coatings based on a composite technology of arc spraying and laser remelting, and the resulting coating. Background Technology

[0002] In aerospace, marine engineering, and power energy fields, critical metal structural components have long faced severe corrosion, wear, and erosion problems, leading to shortened equipment lifespan and high maintenance costs. Traditional surface protection technologies such as electroplating chromium pose environmental pollution problems, while coatings prepared by conventional thermal spraying technologies (such as flame spraying and plasma spraying) often have defects such as high porosity, low bonding strength, and uneven structure, making it difficult to meet the long-term protection requirements of high-end equipment.

[0003] Amorphous alloys (also known as metallic glasses) exhibit far superior corrosion resistance, high hardness, wear resistance, and excellent soft magnetic properties compared to traditional crystalline alloys due to their long-range disordered atomic structure and the absence of crystal defects such as grain boundaries and dislocations. However, the preparation of bulk amorphous alloys is limited by critical dimensions and is costly, which greatly restricts their engineering applications as protective coatings.

[0004] Currently, some studies have attempted to prepare amorphous coatings using thermal spraying technology, but two major technical bottlenecks generally exist: first, amorphous powders are extremely expensive, and the amorphous phase is prone to crystallization during the spraying process; second, the inherent layered structure and porosity defects of the sprayed coating are difficult to eliminate, affecting its protective performance. Although laser cladding technology can prepare dense coatings, the cost of directly cladding amorphous powders remains a significant issue, and it also involves a large heat input to the substrate, which can easily cause deformation.

[0005] Therefore, developing a surface engineering technology that is low-cost, has stable processes, and can produce high-performance amorphous composite coatings has significant engineering application value and market prospects. Summary of the Invention

[0006] Objective of the Invention: The primary objective of this invention is to overcome the shortcomings of existing technologies and provide a low-cost, feasible method for preparing amorphous aluminum-based coatings by arc spraying and laser remelting. Another objective of this invention is to provide an aluminum-based coating prepared by this method that possesses an amorphous / nanocrystalline composite structure, high density, high bonding strength, and excellent overall performance. A further objective of this invention is to provide a dedicated powder-core wire for use in this method.

[0007] Technical solution: The present invention provides a method for preparing a wear-resistant and corrosion-resistant Teflon coating, comprising the following steps: To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing an amorphous aluminum-based coating by arc spraying and then laser remelting includes the following steps: S1. Preparation of powder-core wire: Using industrial pure aluminum strip (such as 1060 aluminum strip) as the outer skin, filling it with alloy powder of a specific formula as the core material, and then rolling it into a U-shape, filling it, joining it, and a series of drawing and diameter reduction processes to produce powder-core wire with a diameter of 1.6-2.0 mm, with the filling rate controlled at 32-40%; S2. Arc spraying: The powder core wire is fed into a high-speed arc spraying equipment, the spraying process parameters are optimized and controlled, and an aluminum-based coating with amorphous phase as the main component is sprayed on the substrate surface; the substrate is actively cooled during the spraying process to control its temperature below 150°C to prevent amorphous phase crystallization. S3. Laser remelting: A laser beam generated by a high-power laser is used to scan and remelt the surface of the amorphous aluminum-based coating obtained in step S2 under a protective atmosphere to eliminate coating pores, optimize the microstructure, and obtain a dense and uniform amorphous / nanocrystalline composite coating.

[0008] Further, in step S1, the alloy powder comprises, by mass percentage: Mg 6-14%, Ti 2-4%, AlNi 1-6%, rare earth element Y or Ce 0.5-2%, with the remainder being Al and unavoidable impurities.

[0009] Furthermore, in step S2, the optimized process parameters for high-speed arc spraying are: spraying current 150-180A, spraying voltage 34-38V, spraying distance 180-220mm, atomizing air pressure 0.65-0.75 MPa, and spray gun moving speed 250-350 mm / s.

[0010] Further, in step S3, the laser used for laser remelting is a semiconductor fiber laser or a CO2 laser, with a laser power of 1.5-3.0 kW, a spot diameter of 2-4 mm, a scanning speed of 5-20 mm / s, and an overlap rate of 30-50%. The protective atmosphere is argon, with a gas flow rate of 15-25 L / min.

[0011] An amorphous aluminum-based composite coating prepared by the above method is characterized in that the coating is a dense amorphous / nanocrystalline composite structure, wherein the amorphous phase content is not less than 60%, the porosity is less than 0.5%, the bonding strength with the substrate is not less than 100 MPa, and the microhardness is not less than HV0.1 350.

[0012] A powder-core wire used in the above method is composed of a pure aluminum outer sheath and an inner alloy powder core; the alloy powder comprises, by mass percentage: Mg 6-14%, Ti 2-4%, AlNi 1-6%, rare earth element Y or Ce 0.5-2%, with the remainder being Al and unavoidable impurities; the powder-core wire has a diameter of 1.6-2.0 mm and a filling rate of 35-38%.

[0013] Compared with the prior art, the present invention has the following significant advantages: Low cost: By using powder core wire technology, low-cost pure aluminum strip and alloy powder are used as raw materials, which cleverly avoids the use of expensive high-purity pre-alloyed amorphous powder, greatly reducing the cost of raw materials.

[0014] Superior performance: The rapid solidification effect of high-speed arc spraying initially forms an amorphous phase, which is then further eliminated by laser remelting to eliminate porosity and homogenize the composition, ultimately resulting in an amorphous / nanocrystalline composite coating. This coating has a dense structure and exhibits extremely high hardness (≥HV0.1 350), excellent bonding strength (≥100 MPa), and outstanding corrosion and wear resistance.

[0015] Good process compatibility: Arc spraying is highly efficient and suitable for large-area and complex-shaped workpieces; laser remelting, as a finishing method, is precise and efficient. The combination of the two forms a complementary composite process route.

[0016] The application prospects are broad: the coating prepared by this method can be widely used in the wear resistance, corrosion protection, remanufacturing and service life extension of key structural components in the fields of shipbuilding, hydropower, chemical industry and energy, which has great economic and social benefits.

[0017] Figure 1 SEM images of the surface and cross-section of the coating prepared in Example 1 after laser remelting (extremely low porosity). Figure 2 The image shows a surface SEM image (high porosity) of Comparative Example 1 (conventional arc-sprayed Al coating). Figure 3 This is a comparison of the electrochemical polarization curves of the coating in Example 1 and the coating in Comparative Example 1. Example

[0018] Preparation of powder-core wire: Weigh the following alloy powders by mass percentage: Mg 6-14%, Ti 2-4%, AlNi 1-6%, rare earth element Y or Ce 0.5-2%, with the balance being Al powder. After uniform mixing, fill the mixture into a 0.3 mm thick 1060 pure aluminum strip, and draw it into a powder-core wire with a diameter of 2.0 mm, with a filling rate of 36%.

[0019] Arc spraying: Using Q345 steel as the substrate, after sandblasting for roughening, high-speed arc spraying equipment is used for spraying. Parameter settings are: current 160 A, voltage 36 V, spraying distance 200 mm, atomizing air pressure 0.7 MPa, and spray gun moving speed 300 mm / s. Compressed air is used to cool the substrate during spraying, and the temperature is controlled below 120℃.

[0020] Laser remelting: A 2.0 kW semiconductor fiber laser was used to remelt the sprayed coating. The parameters were: spot diameter 3 mm, scanning speed 10 mm / s, overlap rate 40%, and argon gas was introduced at a rate of 20 L / min for protection.

[0021] Comparative Example 1 Pure aluminum wire (ER1100) was sprayed using conventional electric arc spraying equipment, and the remaining steps were the same as in Example 1.

[0022] Performance Tests and Results The coatings obtained in Example 1 and Comparative Example 1 were subjected to performance tests: Microstructure: such as Figure 1 and Figure 2 As shown, the coating of Example 1 is extremely dense after laser remelting, with a porosity of <0.5%; while the coating of Comparative Example 1 has obvious pores and a layered structure, with a porosity of >5%.

[0023] Bond strength: The coating bond strength of Example 1 reached 115 MPa (ASTM C633 standard), while the coating bond strength of Comparative Example 1 was 38 MPa.

[0024] Microhardness: The microhardness of the coating in Example 1 was HV0.1 420, and the microhardness of the coating in Comparative Example 1 was HV0.1 60.

[0025] Electrochemical performance: tested in 3.5 wt% NaCl solution ( Figure 3 The self-corrosion potential (Ecorr) of the coating in Example 1 shifted significantly to the positive direction, and the corrosion current density (Icorr) was much lower than that of the coating in Comparative Example 1, demonstrating excellent corrosion resistance.

[0026] The above results show that the coating prepared by this invention has far superior performance in all aspects compared to traditional arc-sprayed aluminum coatings.

[0027] In summary, this invention successfully provides a low-cost, high-efficiency method for preparing high-performance amorphous aluminum-based coatings, solving a long-standing technical problem in this field.

Claims

1. A method for preparing an amorphous aluminum-based coating by arc spraying and then laser remelting, characterized in that, Includes the following steps: S1. Preparation of powder core wire: Using pure aluminum strip as the outer skin, filling it with a core material composed of alloy powder, and then rolling and drawing it to produce powder core wire; S2, Arc spraying: The powder core wire is fed into a high-speed arc spraying device to form an amorphous aluminum base coating on the substrate surface. S3. Laser remelting: The surface of the amorphous aluminum-based coating obtained in step S2 is scanned and remelted using a laser beam to obtain a dense amorphous / nanocrystalline composite coating.

2. The method according to claim 1, characterized in that, In step S1, the alloy powder comprises, by mass percentage: Mg 6-14%, Ti 2-4%, AlNi 1-6%, rare earth element Y or Ce 0.5-2%, with the remainder being Al and unavoidable impurities; the filling rate of the powder core wire is 32-40%.

3. The method according to claim 1, characterized in that, In step S2, the process parameters for high-speed arc spraying are: spraying current 150-180A, spraying voltage 34-38V, spraying distance 180-220mm, and atomizing air pressure 0.65-0.75MPa.

4. The method according to claim 1, characterized in that, In step S2, the substrate is actively cooled during the spraying process to control the substrate temperature below 280°C. The cooling gas is nitrogen, and the gas pressure is not less than 0.5 MPa.

5. The method according to claim 1, characterized in that, In step S3, the laser used for laser remelting is a semiconductor fiber laser or a CO2 laser, with a laser power of 1.5-3.0 kW, a spot diameter of 2-4 mm, a scanning speed of 5-20 mm / s, and an overlap rate of 30-50%.

6. The method according to claim 1 or 5, characterized in that, In step S3, during the laser remelting process, an inert gas is used to protect the molten pool.

7. An amorphous aluminum-based composite coating prepared by the method according to any one of claims 1 to 6, characterized in that, The coating is a dense amorphous / nanocrystalline composite structure, wherein the amorphous phase content is not less than 60%.

8. The amorphous aluminum-based composite coating according to claim 7, characterized in that, The coating has a porosity of less than 0.5%, a bonding strength with the substrate of not less than 100 MPa, and a microhardness of not less than HV0.1 350.

9. A powder-core wire material, used in the method for preparing an amorphous aluminum-based coating by arc spraying as described in claim 1, characterized in that, The powder core wire is composed of a pure aluminum outer sheath and an inner alloy powder core; the alloy powder composition by mass percentage includes: Mg 6-14%, Ti 2-4%, AlNi 1-6%, rare earth element Y or Ce 0.5-2%, and the remainder is Al and unavoidable impurities.

10. The powder-core filament according to claim 9, characterized in that, The diameter of the core wire is 1.6-2.0 mm, and the filling rate is 35-38%.

Images