Method for preparing crystal-amorphous composite wear-resistant layer on zirconium surface

Abstract

The invention relates to the technical field of surface treatment, in particular to a method for preparing a crystal-amorphous composite wear-resistant layer on a zirconium surface, which comprises the following steps: firstly, determining a proper zirconium-based amorphous alloy system, preparing an electro-deposition solution containing element cations of the alloy system, then pretreating a zirconium workpiece, ultrasonically cleaning by using absolute ethyl alcohol and deionized water, and drying to obtain the crystal-amorphous composite wear-resistant layer on the zirconium surface. Connecting the pretreated zirconium workpiece with a copper wire to prepare a working electrode, carrying out electro-deposition on the surface of the zirconium workpiece by using an electrochemical workstation, carrying out laser surface alloying treatment, placing the workpiece in a laser processing area, and finally observing the structure morphology of the composite layer by using a transmission electron microscope. By analyzing the hardness by using hardness testing equipment and comparing the hardness with a matrix, the wear resistance of the zirconium material can be effectively improved, the problem of poor wear resistance of the zirconium surface is solved, and the hardness of the zirconium surface is improved.

Description

Technical Field

[0001] The present invention relates to surface treatment technology, and more particularly to a method for preparing a crystalline-amorphous composite wear-resistant layer on the surface of zirconium. Background Art

[0002] Due to its excellent mechanical properties, corrosion resistance and high-temperature strength, zirconium is widely used in the nuclear industry, chemical industry and aerospace field. For example, it is used as a fuel cladding in nuclear reactors, for manufacturing corrosion-resistant equipment in the chemical industry, and can be used to manufacture engine components in the aerospace field. However, the disadvantage of zirconium is its poor surface wear resistance. To improve the wear resistance of zirconium, the common practice is to coat an amorphous layer on the metal surface by means of thermal spraying, laser cladding, etc. However, the bonding strength between the amorphous layer and the substrate is low and it is easy to peel off. The reason is that the amorphous coating is hard, the interfacial bonding is poor, and the thermal expansion rate does not match that of the substrate.

[0003] Zirconium can form amorphous alloys with a variety of metal elements. The electrodeposition technique can deposit metals on the surface of zirconium, and combined with laser surface alloying, it is expected to solve the above problems. By controlling the electrodeposition solution 4 and deposition parameters, the element type and thickness of the deposited layer can be regulated. During laser treatment, its high cooling rate can form a crystalline-amorphous composite layer, which combines the matching advantages of the crystalline phase and the wear-resistant characteristics of the amorphous phase, and metallurgically fuses with the substrate, providing a new idea for improving the surface wear resistance of zirconium.

[0004] Patent with application number CN202211293625.2: A method and device for preparing an electrodeposited crystallization / amorphous gradient structure by using a laser remelting process. An Ni-P amorphous coating with good corrosion resistance is prepared on the surface of a workpiece substrate by electrodeposition, and the laser remelting process is used to remove the surface cracks formed when the electrodeposited amorphous alloy is removed, and at the same time, a molten crystallization layer is formed, preparing a three-layer gradient structure of substrate-Ni-P amorphous coating-crystallization remelting layer. The main purpose of laser remelting in this invention is to reduce the voids and cracks in the surface amorphous layer, and form a crystallization remelting layer on the sample surface to obtain a gradient structure, which is completely different from the structure of the uniform dispersion composite of the zirconium-based soft phase (crystalline phase) and hard phase (amorphous phase) constructed in the present invention. At the same time, what is obtained by Ni-P electrodeposition is an amorphous layer, and a crystallization layer is formed by the action of the laser, while what is electrodeposited on the surface of Zr in the present invention is a crystalline layer of Cu and Ni, and an amorphous composite phase is formed by the action of the laser, and the design ideas are completely different. Moreover, for the gradient structure, the laser power needs to be strictly controlled. If the power is too high, the matrix metal will be incorporated, making the surface remelting layer no longer contain the amorphous phase. If the laser power is too low, it is difficult to solve the problem of poor bonding force between the coating and the substrate and cannot completely eliminate the voids and cracks in the amorphous layer, so the controllability is poor.

[0005] The patent with the application number CN202110941303.3: A method and device for preparing a gradient coating by laser-assisted electrodeposition directly supplements pulsed laser during the electrodeposition process to obtain a layered structure. The purpose of this structure is to eliminate the interface between the coating material and the substrate material, promote the bonding between the coating and the substrate, and improve the coating peeling phenomenon, which is completely different from the present invention of obtaining an amorphous-crystalline composite phase to enhance surface hardness and wear resistance.

[0006] The patent with the application number CN201510246454.1: The electrodeposition-laser remelting strengthening process for Ni-nano-TiN composite layer on the surface of nickel-based superalloy obtains a crystalline nano-composite coating. The purpose of the laser remelting used is to improve the bonding force between the coating and the substrate, improve the flatness and density of the coating surface, and reduce defects. While the present invention constructs a composite layer of a zirconium-based soft phase (crystalline phase) and a hard phase (amorphous phase), and the role of laser surface alloying is to promote the transformation of the coating from the crystalline phase to the amorphous phase.

[0007] The patent with the application number CN202110021483.3: A method for improving the surface hardness of zirconium-based amorphous alloys by nanosecond laser carbonization introduces zirconium carbide hard particles on the surface of zirconium-based amorphous through pulsed laser to improve hardness and wear resistance. While the present invention electro-deposits on the crystalline zircon surface and then continuously laser remelts to obtain a crystal-amorphous composite structure, with completely different ideas and implementation methods.

[0008] The Japanese patent with the publication number JP2019512597A discloses a substrate coated with a hard material coating, and this coating includes a hard carbon film of the hydrogen-free amorphous carbon film type. A carbon film and a film made of Zr-Cx can be constructed between the film made of zirconium and the hydrogen-free amorphous carbon film. Among them, a zirconium-containing monocarbide film is formed directly on the bonding film made of zirconium, but the bonding performance is poor, which limits its application range.

[0009] Therefore, it is necessary to propose a method for preparing a crystal-amorphous composite wear-resistant layer on the zircon surface in order to partially solve the above problems. Summary of the Invention

[0010] In order to better solve the above problems, the present invention provides a method for preparing a crystal-amorphous composite wear-resistant layer on the zircon surface, and the method includes the following steps:

[0011] Step S1: Determine a suitable zirconium-based amorphous alloy system and configure an electrodeposition solution containing cations of the alloy system elements;

[0012] Step S2: Pretreat the zircon workpiece;

[0013] Step S3: Connect the pretreated zircon workpiece with a copper wire to make a working electrode;

[0014] Step S4: Electrochemical deposition is carried out on the surface of the zirconium workpiece using an electrochemical workstation to obtain a metal reduction coating;

[0015] Step S5: Laser surface alloying treatment is carried out based on the metal reduction coating to form an alloy remelting layer;

[0016] Step S6: The remelting layer is remelted multiple times to obtain a crystal-amorphous composite layer prepared on the surface of zirconium.

[0017] As a more preferred technical solution of the present invention, the zirconium-based amorphous alloy system in step S1 is a zirconium-copper-nickel system, and the electroplating solution includes a copper sulfate solution and a nickel sulfate solution. Among them, when depositing copper, the electroplating solution is the copper sulfate solution, and when depositing nickel, the electroplating solution is the nickel sulfate solution.

[0018] As a more preferred technical solution of the present invention, the process of obtaining the metal reduction coating includes:

[0019] First deposit copper for 10 minutes with a current density of 60 mA / cm², and then deposit nickel for 10 minutes with a current density of 30 mA / cm².

[0020] As a more preferred technical solution of the present invention, in step S5, before the laser surface alloying treatment, the electroplated zirconium workpiece is dried at a drying temperature of 60 °C for 30 minutes.

[0021] As a more preferred technical solution of the present invention, in step S5, the laser power is set to 500 W, the scanning speed is 10 mm / s, argon is selected as the shielding gas, the gas flow rate is 5 L / min, and the surface remelting zone overlap rate is 50% to form an alloy remelting layer;

[0022] When remelting the alloy remelting layer, the laser power, scanning speed, type of shielding gas and gas flow rate for each remelting are the same as those in the initial laser surface alloying treatment.

[0023] As a more preferred technical solution of the present invention, during the ultrasonic cleaning process, during the pretreatment process of the zirconium workpiece in step S2, it is polished successively with 400#, 800#, 1200#, 1500#, and 2000# sandpapers;

[0024] During the ultrasonic cleaning process, the ultrasonic cleaning time for both anhydrous ethanol and deionized water is 2 minutes.

[0025] As a more preferred technical solution of the present invention, in step 5, during the laser surface alloying treatment, the spot diameter of the laser beam is 1 mm.

[0026] As a more preferred technical solution of the present invention, after obtaining the composite layer in step S6, it further includes observing the tissue morphology of the composite layer using a transmission electron microscope, and analyzing its hardness using a hardness testing device and comparing it with the substrate.

[0027] As a more preferred technical solution of the present invention, in step S1, before determining the zirconium-based amorphous alloy system, the amorphous formation ability of the candidate alloy systems is tested, and the system with strong amorphous formation ability is selected.

[0028] As a more preferred technical solution of the present invention, during the electro-deposition process, in the electro-deposition process of step S4, the electro-deposition solution is stirred, and the stirring speed is 100 r / min.

[0029] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0030] In the present invention, by pre-treating the zirconium workpiece, removing its surface oxide layer and impurities by sequentially polishing with 400#, 800#, 1200#, 1500#, and 2000# sandpapers, and then ultrasonically cleaning with anhydrous ethanol and deionized water, a clean and flat surface is provided for subsequent processing. Then, a suitable zirconium-based amorphous alloy system is determined and the corresponding electro-deposition solution is prepared. The treated zirconium workpiece is made into a working electrode, and electro-deposition is carried out using an electrochemical workstation. In this process, by precisely controlling the current density at 60 mA / cm² and the deposition time at 10 min, the thickness of the Cu deposition layer can be accurately regulated, and by controlling the current density at 30 mA / cm² and the deposition time at 10 min, the thickness of the Ni deposition layer can be accurately regulated, enabling customized preparation of the deposition layer. In addition, after electro-deposition, laser surface alloying treatment is carried out. The workpiece is placed in the laser processing area, and argon is selected as the protective gas. Its flow rate of 5 L / min effectively prevents oxidation. By setting the laser power at 500 W, the scanning speed at 10 mm / s, and the surface remelting zone overlap rate at 50%, the deposition layer and the surface layer of the zirconium substrate are fully fused to form an alloy remelting layer. Then, the remelting layer is remelted twice to further improve its uniformity. Finally, a crystal-amorphous composite layer is obtained, thereby realizing precise control of the process parameters, making it applicable to a variety of zirconium-based amorphous alloy systems, meeting the diverse requirements for zirconium surface properties in different fields, and moreover, the entire preparation process has relatively simple steps, is easy to operate, requires common equipment, has a low cost, and a short production cycle. Description of the Drawings

[0031] Figure 1 It is a flowchart of a method for preparing a crystal-amorphous composite wear-resistant layer on the surface of zirconium according to the present invention;

[0032] Figure 2 It is a schematic diagram of an electro-deposition device in a method for preparing a crystal-amorphous composite wear-resistant layer on the surface of zirconium according to the present invention;

[0033] Figure 3 Macromorphology of the specimen after electrodeposition in a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface according to the present invention;

[0034] Figure 4 Schematic diagram of the laser surface alloying device in a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface according to the present invention;

[0035] Figure 5 Schematic diagram of the macromorphology of the laser surface alloying specimen in a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface according to the present invention;

[0036] Figure 6 Cross-sectional microstructure morphology diagrams of laser surface alloying in a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface according to the present invention: (a) low magnification and (b) high magnification schematic diagrams;

[0037] Figure 7 Morphology and structure analysis of a crystalline-amorphous composite layer on zirconium surface according to the present invention: (a) composite characteristics of ordered and disordered atomic arrangements and (b) electron diffraction pattern;

[0038] Figure 8 Hardness schematic diagram of the zirconium substrate and the crystalline-amorphous composite layer on the zirconium surface in a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface according to the present invention.

[0039] In the figure: 1. Zirconium material 1; 2. Auxiliary electrode; 3. Reference electrode; 4. Electrodeposition solution; 5. Electrochemical workstation; 6. Argon inlet pipe; 7. Zirconium material 2; 8. Inert gas protection cover; 9. Laser scanning head. Detailed implementation manners

[0040] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] The present invention provides a method for preparing a crystalline-amorphous composite wear-resistant layer on zirconium surface, as Figure 1 shown, the method includes the following steps:

[0042] Step S1: Determine a suitable zirconium-based amorphous alloy system as the zirconium-copper-nickel system, and configure two electrodeposition solutions containing cations of the alloy system elements, that is, configure a saturated copper sulfate solution and a saturated nickel sulfate solution respectively.

[0043] Specifically, first, based on the characteristics of the zirconium-based amorphous alloy system and the performance requirements of the target composite wear-resistant layer, a suitable zirconium-based amorphous alloy system is determined by referring to relevant literature, referring to past experimental data, and conducting preliminary experimental verification. Then, according to the chemical composition of the alloy system, an electroplating solution containing corresponding elemental cations is accurately calculated and prepared. For example, for the zirconium-copper-nickel system, a saturated copper sulfate solution and a nickel sulfate solution are respectively prepared so that the solution contains copper ions and nickel ions. These cations will move towards the cathode (zirconium workpiece) under the action of an electric field during the subsequent electroplating process, solving the problem of how to provide a suitable ion source for the subsequent electroplating process. In addition, different zirconium-based amorphous alloy systems have different performance characteristics. Selecting a suitable system and preparing the corresponding electroplating solution can ensure the formation of a composite wear-resistant layer with specific composition and performance on the zirconium surface, meeting the requirements for wear resistance, hardness, etc. under different working conditions.

[0044] Step S2: Pretreat the zirconium workpiece by successively polishing it with 400#, 800#, 1200#, 1500#, and 2000# sandpapers, and then ultrasonically cleaning it with anhydrous ethanol and deionized water.

[0045] Specifically, first, the zirconium workpiece is successively polished with sandpapers of different mesh numbers. Through the frictional action between the abrasive grains on the sandpaper surface and the surface of the zirconium workpiece, the oxide layer, impurities, and uneven parts on the surface of the zirconium workpiece are gradually removed. As the mesh number of the sandpaper increases, the abrasive grains become finer and the polished surface becomes smoother. Then, the polished zirconium workpiece is placed in anhydrous ethanol and deionized water for ultrasonic cleaning. Using the cavitation effect generated by ultrasonic waves in the liquid, a large number of tiny bubbles are formed in the liquid. These bubbles generate a strong impact force during the process of rapid growth and closure, which can completely remove the tiny particles and oil stains and other impurities attached to the surface of the zirconium workpiece, solving the problems of the existence of oxide layer, impurities, and unevenness on the surface of the zirconium workpiece. Through pretreatment, a clean and flat surface of the zirconium workpiece can be obtained, laying a foundation for high-quality electroplating and the formation of a composite wear-resistant layer.

[0046] Step S3: Connect the pretreated zirconium workpiece to a copper wire to form a working electrode.

[0047] Specifically, first, the pretreated zirconium workpiece is reliably connected to the copper wire. Through this connection method, the zirconium workpiece can be connected to the circuit of the electrochemical workstation 5. During the electroplating process, the current provided by the electrochemical workstation 5 can be conducted to the zirconium workpiece through the copper wire, making the zirconium workpiece become the cathode and attracting the cations in the electroplating solution under the action of an electric field, thereby realizing the reduction and deposition of metal ions, solving the problem of how to connect the zirconium workpiece to the electroplating circuit. Only by making the zirconium workpiece into a suitable working electrode can it be ensured that the electroplating process can proceed smoothly and the metal ions can be reduced to form a coating on the surface of the zirconium workpiece.

[0048] Step S4: Electro-deposit on the surface of the zircon workpiece using an electrochemical workstation 5. The current densities are: for Cu plating: 60 mA / cm², for Ni plating: 30 mA / cm², and the deposition time is 10 min for both, to obtain a metal reduction coating.

[0049] Specifically, first place the fabricated working electrode (zircon workpiece), counter electrode, and reference electrode 3 together into the prepared electro-deposition solution and connect them to the electrochemical workstation 5. The electrochemical workstation 5 applies a certain current, causing metal cations (such as copper ions, nickel ions, etc.) in the electro-deposition solution to move towards the cathode (zircon workpiece) under the action of the electric field, and obtain electrons on the surface of the zircon workpiece to undergo a reduction reaction, thereby depositing to form a metal coating. By precisely controlling the current density and deposition time, the reduction rate and deposition amount of metal ions can be controlled, and thus the thickness and quality of the coating can be controlled, solving the problem of how to precisely control the formation of a metal coating with a certain thickness and quality on the surface of the zircon workpiece. In addition, appropriate current density and deposition time can ensure that the coating grows uniformly and densely and has a good bonding force with the zircon substrate, providing a basis for the subsequent formation of a crystal-amorphous composite wear-resistant layer.

[0050] Step S5: Perform laser surface alloying treatment. Place the workpiece in the laser processing area. The laser power is 500 W, the scanning speed is 10 mm / s, argon is selected as the shielding gas, the gas flow rate is 5 L / min, and the overlap rate of the surface remelting zone is 50%, to form an alloy remelting layer.

[0051] Specifically, first place the electro-deposited zircon workpiece in the laser processing area, turn on the laser equipment. Through the high-energy irradiation of the laser beam, the metal coating on the surface of the zircon workpiece and part of the zircon substrate are rapidly melted. During this process, argon is selected as the shielding gas and blown towards the processing area at a certain flow rate (5 L / min). The inertness of argon can prevent the melted metal from undergoing oxidation reactions with oxygen in the air at high temperatures. At the same time, by precisely controlling the laser power, scanning speed, and overlap rate of the surface remelting zone, the melted metal can be fully mixed and rapidly cooled and solidified to form an alloy remelting layer. The laser power determines the melting degree and depth of the metal, the scanning speed affects the heating and cooling speeds of the metal, and the overlap rate of the surface remelting zone ensures that the entire surface of the zircon workpiece can be evenly treated, solving the problem of how to fuse the metal coating formed by electro-deposition with the zircon substrate to form an alloy remelting layer with good properties. The bonding force between the traditional coating and the substrate is weak and easy to peel off, while laser surface alloying treatment can achieve metallurgical bonding between the coating and the substrate, improving the bonding strength. At the same time, through the rapid cooling process, an amorphous phase can be formed in some areas, jointly constituting a crystal-amorphous composite structure with the crystal phase to enhance the wear resistance.

[0052] Step S6: Observe the microstructure morphology of the composite layer using a transmission electron microscope, and analyze its hardness using a hardness testing device and compare it with the substrate.

[0053] Specifically, first, use a transmission electron microscope to observe the prepared composite layer. The electron beam penetrates the composite layer sample. Due to the different atomic arrangements of the crystal phase and the amorphous phase, there are differences in the electron scattering ability, resulting in different contrasts on the image, enabling clear observation of the distribution, morphology, and size of the crystal phase and the amorphous phase and other microstructural features. Then, use a hardness testing device (such as a Vickers hardness tester, nanoindentation instrument, etc.) to test the hardness of the composite layer and the zirconium substrate. By applying a certain pressure and measuring the size of the indentation, the hardness value is obtained. Compare the hardness value of the composite layer with the hardness value of the substrate, which solves the problem of how to evaluate the quality and performance of the prepared crystal-amorphous composite wear-resistant layer. By observing the microstructure morphology, it can be understood whether the microstructure of the composite layer meets the expectations and whether an ideal crystal-amorphous composite structure is formed. Comparing the hardness values can intuitively show the improvement of the composite layer in terms of hardness relative to the zirconium substrate, thereby determining whether the composite wear-resistant layer meets the expected wear-resistant performance requirements and providing a basis for further optimizing the preparation process.

[0054] The zirconium-based amorphous alloy system is a zirconium-copper-nickel system. The electrodeposition solution includes a copper sulfate solution and a nickel sulfate solution. Among them, when depositing copper, the electrodeposition solution is the copper sulfate solution, and when depositing nickel, the electrodeposition solution is the nickel sulfate solution.

[0055] Specifically, first, determine the zirconium-copper-nickel system as the zirconium-based amorphous alloy system because this system has a strong ability to form amorphous. The electrodeposition solution includes a copper sulfate solution and a nickel sulfate solution. Among them, when depositing copper, the electrodeposition solution is the copper sulfate solution, and when depositing nickel, the electrodeposition solution is the nickel sulfate solution. Copper ions Cu 2+ and nickel ions Ni 2+ will be dissociated in the solution respectively. During the electrodeposition process, these cations move towards the cathode (zirconium workpiece) under the action of the electric field and obtain electrons on the surface of the zirconium workpiece to undergo a reduction reaction, thereby depositing copper and nickel in sequence.

[0056] Copper and nickel fuse with zirconium during the subsequent laser surface alloying process. Utilizing the interatomic forces and diffusion mechanisms between them, a crystal-amorphous composite structure with specific properties is formed, thus solving the problem of selecting a suitable alloy system and electrodeposition solution to form a crystal-amorphous composite wear-resistant layer with good performance. The zirconium-copper-nickel system can provide a suitable element combination, which is conducive to forming a stable composite structure of the amorphous phase and the crystal phase during laser treatment. The copper sulfate solution and the nickel sulfate solution respectively provide the necessary Cu 2+ and Ni 2+The ion source ensures the smooth progress of the deposition process and the accuracy of the coating composition.

[0057] During the electrodeposition process, copper was deposited first, with a deposition time of 10 min and a current density of 60 mA / cm², and then nickel was deposited, with a deposition time of 10 min and a current density of 30 mA / cm².

[0058] Specifically, at the beginning of the electrodeposition, the electrochemical workstation 5 is controlled to deposit at a current density of 60 mA / cm² for 10 minutes, so that the copper ions undergo a reduction reaction on the surface of the zirconium workpiece and a layer of copper is deposited. This is because copper has good conductivity and certain corrosion resistance. The first deposition of copper can provide a good base for the subsequent deposition of nickel and improve the bonding performance of the coating with the zirconium substrate. Then, the current density is adjusted to 30 mA / cm² for deposition for 10 minutes to deposit nickel ions on the copper layer. Through this step-by-step deposition method, the thickness and quality of the copper layer and the nickel layer are controlled by different current densities and times. In the subsequent laser surface alloying process, the copper layer and the nickel layer diffuse and fuse with the zirconium substrate to form a crystal-amorphous composite structure, which solves the problem of how to optimize the electrodeposition process to improve the performance of the composite wear-resistant layer. The step-by-step deposition of copper and nickel can avoid the problems of poor bonding and uneven composition that may occur in the deposition of a single metal. Different current density and time settings can accurately control the thickness and quality of the copper layer and the nickel layer, thereby affecting the microstructure and performance of the final composite wear-resistant layer, such as improving the hardness, wear resistance and bonding strength of the composite layer.

[0059] Before the laser surface alloying treatment, the electrodeposited zirconium workpiece was dried at a temperature of 60°C for 30 minutes.

[0060] Specifically, the zirconium workpiece after electrodeposition is first placed in a drying device, and the drying temperature is set to 60°C and the time is 30 minutes. The heat transfer principle is used to gradually evaporate the moisture on the surface and inside of the workpiece. During the drying process, the increase in temperature will increase the kinetic energy of the water molecules, causing them to change from liquid to gas and detach from the workpiece surface. The appropriate temperature and time settings can ensure that the moisture is fully removed, while avoiding oxidation or deformation of the coating due to excessive temperature, and solve the problem of the influence of residual moisture on the workpiece surface after electrodeposition on the laser surface alloying treatment. The presence of moisture may vaporize rapidly during the laser heating process to produce bubbles, resulting in defects such as pores and cracks in the alloy remelting layer, affecting the quality and performance of the composite wear-resistant layer. The drying treatment can ensure the stability and reliability of the laser surface alloying process and improve the density and bonding strength of the composite wear-resistant layer.

[0061] When the alloy remelting layer is remelted, the laser power, scanning speed, type of shielding gas and flow rate of each remelting are the same as those of the initial laser surface alloying treatment.

[0062] Specifically, when performing the remelting operation of the alloy remelting layer, keep the laser power, scanning speed, type and flow rate of the protective gas the same as those in the initial laser surface alloying treatment. The laser power determines the energy density of the laser beam, which controls the melting degree and depth of the alloy remelting layer. The scanning speed affects the heating and cooling rates of the alloy remelting layer and plays an important role in the formation of amorphous and crystalline phases. The protective gas (argon) and its flow rate prevent the alloy remelting layer from oxidizing at high temperatures. By keeping these parameters unchanged, the repeatability and consistency of each remelting process can be ensured, further promoting the uniform diffusion and mixing of elements inside the alloy remelting layer, improving the microstructure and properties of the composite wear-resistant layer, and solving the problem of how to optimize the performance of the alloy remelting layer through multiple remelting processes. The initial laser surface alloying treatment may not be able to achieve the ideal uniformity and performance of the alloy remelting layer. Multiple remelting and maintaining consistent parameters can make the alloy remelting layer denser, reduce defects, and improve the stability and uniformity of the crystal-amorphous composite structure, thereby further enhancing the hardness, wear resistance, and bonding strength of the composite wear-resistant layer.

[0063] During the ultrasonic cleaning process, the ultrasonic cleaning time for both anhydrous ethanol and deionized water is 2 minutes.

[0064] Specifically, first place the zircon workpieces polished with sandpaper into anhydrous ethanol and deionized water respectively for ultrasonic cleaning. When the ultrasonic waves generated by the ultrasonic equipment propagate in the liquid, cavitation effects will occur, forming a large number of tiny bubbles in the liquid. These bubbles generate a strong impact force during the rapid growth and closure process, which can peel off the tiny particles, oil stains, and impurities attached to the surface of the zircon workpieces from the workpiece surface. Anhydrous ethanol has good solubility and can remove organic impurities such as oil stains on the workpiece surface, while deionized water can further wash away the remaining impurities and ethanol, solving the problem of how to effectively remove the impurities on the surface of the zircon workpieces to ensure the quality of subsequent processing. If the ultrasonic cleaning time is too short, the impurities may not be completely removed, and if the time is too long, it may cause damage to the workpiece surface. The 2-minute ultrasonic cleaning time can ensure the cleaning effect while avoiding adverse effects on the workpiece surface, providing a clean workpiece surface for subsequent electroplating and laser surface alloying treatment, which is beneficial to improving the quality and performance of the composite wear-resistant layer.

[0065] During the laser surface alloying treatment, the spot diameter of the laser beam is 1 mm.

[0066] Specifically, first during the laser surface alloying process, by adjusting the optical system of the laser equipment, the spot diameter of the laser beam is controlled to be 1 mm. The spot diameter determines the area of the laser beam irradiated on the surface of the zirconium workpiece, thereby affecting the distribution and effect of the laser energy. A smaller spot diameter can make the laser energy more concentrated, increase the energy density, facilitate rapid heating and cooling, and promote the formation of the amorphous phase. A larger spot diameter can expand the processing area and improve the processing efficiency. By selecting an appropriate spot diameter, while ensuring the processing effect, the processing efficiency can be taken into account, solving the problem of how to optimize the laser surface alloying processing parameters to improve the quality of the composite wear-resistant layer and the processing efficiency. An inappropriate spot diameter may lead to uneven energy distribution and affect the quality of the alloy remelting layer, such as local overheating or insufficient heating. A spot diameter of 1 mm can form an appropriate energy distribution on the surface of the zirconium workpiece, making the formation of the alloy remelting layer more uniform and improving the quality and performance of the crystal-amorphous composite structure. At the same time, the processing time is reasonably controlled to improve the production efficiency.

[0067] Before determining the zirconium-based amorphous alloy system, the amorphous forming ability of the candidate alloy systems is tested, and the system with strong amorphous forming ability is selected.

[0068] Specifically, first, a variety of candidate zirconium-based amorphous alloy systems are collected, and their amorphous forming abilities are tested through a series of experimental methods. For example, differential scanning calorimetry (DSC) is used to measure parameters such as the width of the supercooled liquid region and the glass transition temperature of the alloy. The wider the supercooled liquid region and the higher the glass transition temperature, usually indicating that the amorphous forming ability of the alloy system is stronger. It is also possible to observe whether the alloy can form an amorphous structure during the rapid cooling process through rapid solidification experiments. By analyzing and comparing these test results, the alloy system with strong amorphous forming ability is selected. In the subsequent laser surface alloying process, the alloy system with strong amorphous forming ability is more likely to form an amorphous phase during the rapid cooling process and jointly form a crystal-amorphous composite structure with the crystal phase, solving the problem of how to select an appropriate zirconium-based amorphous alloy system to form an ideal crystal-amorphous composite wear-resistant layer. Different zirconium-based amorphous alloy systems have different amorphous forming abilities. Selecting the alloy system with strong amorphous forming ability can increase the proportion and stability of the amorphous phase in the composite wear-resistant layer, thereby improving the hardness, wear resistance and other properties of the composite wear-resistant layer.

[0069] During the electroplating process, the electroplating solution is stirred at a stirring speed of 100 r / min.

[0070] Specifically, first during the electroplating process, a stirring device is used to stir the electroplating solution at a speed of 100 r / min. Stirring enables the ions in the electroplating solution to be more evenly distributed in the solution, avoiding local deposition rate differences caused by uneven ion concentration. At the same time, stirring can also promote the diffusion of ions to the surface of the cathode (zirconium workpiece), improve the mass transfer efficiency of ions, and enable metal ions to reach the surface of the zirconium workpiece in a more timely manner for reduction reactions. Under the action of stirring, the temperature in the electroplating solution is also more uniform, which is conducive to forming a uniform and dense coating, solving the problems of uneven ion concentration and low mass transfer efficiency during the electroplating process. Uneven ion concentration may lead to problems such as uneven coating thickness and inconsistent composition, while low mass transfer efficiency will affect the deposition rate and coating quality. By stirring the electroplating solution, the stability of the electroplating process and the quality of the coating can be improved, making the finally formed crystal-amorphous composite wear-resistant layer more uniform and dense, and improving its performance and reliability.

[0071] In summary, first select a metal element system with strong amorphous formation ability with zirconium, such as the zirconium-copper-nickel system. According to the selected alloy system, prepare an electroplating solution containing cations of the corresponding metal elements. The electroplating solution includes copper sulfate solution and nickel sulfate solution. Among them, when depositing copper, the electroplating solution is copper sulfate solution, and when depositing nickel, the electroplating solution is nickel sulfate solution, providing an ion source for subsequent electroplating. This step is the basis of the entire process. The appropriate alloy system and electroplating solution determine the composition and potential performance of the final composite layer. Subsequently, use 400#, 800#, 1200#, 1500#, and 2000# sandpapers to polish the surface of the zirconium workpiece in sequence, gradually removing the surface oxide layer, processing marks, and impurities, reducing the surface roughness. Coarse sandpapers (such as 400#) first remove larger defects and oxide layers. As the grit number of the sandpaper increases, the abrasive grains become finer, and the surface is refined, making the surface smoother and providing a good substrate for subsequent electroplating.

[0072] The polished zirconium workpiece is ultrasonically cleaned with absolute ethanol and deionized water for two minutes in sequence. Ultrasonic cleaning utilizes the cavitation effect generated when ultrasonic waves propagate in a liquid. The high-frequency vibration of ultrasonic waves causes countless tiny bubbles to be generated inside the liquid. These bubbles burst instantly when they come into contact with the surface of the zirconium workpiece, generating a strong impact force, peeling off the tiny particles, oil stains, and other impurities attached to the surface. Absolute ethanol can dissolve organic substances such as oil stains, and deionized water further rinses off the residual impurities and ethanol, ensuring the cleanliness of the surface of the zirconium workpiece and avoiding impurities from affecting the bonding strength between the electroplated layer and the substrate.

[0073] The processed zirconium workpiece is connected to a copper wire to prepare a working electrode. In the principle of electrochemistry, the working electrode is the site where the electrochemical reaction occurs. Through the connection of the copper wire, the zirconium workpiece is connected to the circuit of the electrochemical workstation 5 and serves as the cathode during the electroplating process, attracting metal cations in the electroplating solution and providing conditions for the reduction and deposition of metal ions.

[0074] Secondly, the working electrode (zirconium workpiece), the auxiliary electrode 2, and the reference electrode 3 are placed in the prepared electroplating solution and connected to the electrochemical workstation 5. The electrochemical workstation 5 provides direct current. Under the action of the electric field, metal cations (such as copper ions and nickel ions) in the electroplating solution move towards the cathode (zirconium workpiece). According to the principle of electrochemical deposition, the cations gain electrons on the cathode surface and undergo a reduction reaction, thereby depositing on the surface of the zirconium workpiece to form a metal coating. By controlling the current density and deposition time (Cu: current density is 60 mA / cm², deposition time is 10 min; Ni: current density is 30 mA / cm², deposition time is 10 min), the deposition rate and deposition amount of metal ions can be precisely controlled, and further the thickness and composition of the coating can be controlled. For example, a higher current density and a longer deposition time will thicken the coating. Depositing copper first and then nickel, the copper layer can serve as the bottom layer to improve the bonding performance between the nickel layer and the zirconium substrate. And different deposition parameters (such as current density and time) will affect the structure and performance of the copper layer and the nickel layer, ultimately affecting the overall performance of the composite layer.

[0075] Then the electroplated workpiece is placed in the laser processing area, and the laser scanning head 9 is turned on. The laser has the characteristic of high energy density and irradiates the deposited layer and the surface layer of the zirconium substrate at a power of 500 W. According to the principle of the interaction between the laser and the material, after the material absorbs the laser energy, the temperature rises rapidly, causing the deposited layer and part of the surface layer of the zirconium substrate to reach the melting state in a short time and form a molten pool. During this process, argon is selected as the protective gas, and the gas flow rate is 5 L / min. Argon is an inert gas and is chemically stable at high temperatures. During the laser processing, argon continuously blows towards the surface of the molten pool, forming a protective barrier to prevent oxygen, nitrogen, etc. in the air from reacting with the high-temperature molten metal, avoiding phenomena such as oxidation and nitridation, and improving the purity and performance of the composite layer.

[0076] Subsequently, the laser scanning speed is selected as 10 mm / s. The scanning speed determines the action time of the laser per unit area. A faster scanning speed causes the molten pool to cool rapidly, which is beneficial to the formation of a fine-grained structure. A slower scanning speed allows the heat to transfer more fully in the material, promoting element diffusion and uniform mixing. The overlap rate of the surface remelting zone is 50%. The appropriate overlap rate ensures that the entire surface of the workpiece can be evenly processed, avoiding the occurrence of unfused areas, making the alloy remelting layer continuous and uniform, and ensuring the quality and performance consistency of the composite layer.

[0077] In addition, the alloy remelting layer is remelted twice. The laser power, scanning speed, type of protective gas and gas flow rate for each remelting are the same as those during the initial laser surface alloying treatment. During the remelting process, the laser reheats the molten pool again, enabling further diffusion and uniform mixing of alloying elements. Due to the extremely high laser cooling rate (generally up to 105 - 108 K / s), the conditions for amorphous formation are met. According to the amorphous formation theory, during the rapid cooling process, atoms are frozen before they can be regularly arranged, thus forming an amorphous phase in some areas of the deposition layer, while the remaining part of the deposition layer still retains the crystalline phase. Eventually, a crystal - amorphous composite layer is obtained. Multiple remelting can improve the uniformity of the remelting layer, reduce composition segregation and tissue defects, and optimize the structure and properties of the crystal - amorphous composite layer.

[0078] It should be noted that: when the electrochemical workstation 5 is powered on and the parameters are set (current density of Cu: 60 mA / cm², Ni: 30 mA / cm², and deposition time of 10 min for both), under the action of the electric field, metal cations (such as copper ions and nickel ions) in the electrodeposition solution 4 migrate towards the surface of the zirconium material acting as the cathode, while electrons flow from the electrochemical workstation 5 to the zirconium material through the external circuit. The metal cations reaching the surface of the zirconium material gain electrons, undergo a reduction reaction and deposit on the surface of the zirconium material, gradually forming a metal deposition layer. The auxiliary electrode 2 acts as the anode, undergoing an oxidation reaction to maintain the smoothness of the current loop. The reference electrode 3 monitors the potential of the working electrode in real - time. The electrochemical workstation 5 automatically adjusts the output voltage according to the potential information fed back by the reference electrode 3 to ensure that the electrodeposition process proceeds stably within the set current parameter range until the predetermined deposition time is reached, completing the preparation of the metal deposition layer.

[0079] During the first experiment, the zirconium - copper - nickel system was selected. First, copper was electrodeposited with a deposition time of 10 min and a current density of 60 mA / cm², then nickel was electrodeposited with a deposition time of 10 min and a current density of 30 mA / cm². The laser power used for laser alloying was 500 W, the spot diameter of the laser beam was 1 mm, the scanning speed was 10 mm / s, argon was selected as the protective gas with a gas flow rate of 5 L / min, the overlap rate of the surface remelting area was 50%, the thickness of the alloy remelting layer formed was 100 μm, a uniform composite structure was obtained, and the hardness was increased to 355 HV.

[0080] If the deposition time is adjusted to 15 min with a current density of 60 mA / cm², then nickel is electrodeposited with a deposition time of 15 min and a current density of 30 mA / cm². The laser power is set to 300 W, the spot diameter of the laser beam is 1 mm, the scanning speed is 5 mm / s, argon is selected as the protective gas with a gas flow rate of 5 L / min, the overlap rate of the surface remelting area is 60%, the thickness of the alloy remelting layer formed is 140 μm, a uniform composite structure is obtained, and the hardness is increased to 380 HV.

[0081] It should be noted that: the increase in the surface hardness of zirconium materials can improve wear resistance, but excessive hardness will also increase brittleness. Although the above experimental data obtained the highest surface hardness of 380 HV, it was found that its brittleness increased during hardness testing, which made the comprehensive performance of the wear-resistant layer inferior to that of the sample with 355 HV. Therefore, the experimental data of the sample with 355 HV were used to prepare a crystal-amorphous composite wear-resistant layer with moderate hardness and no obvious brittleness.

[0082] If the deposition time is adjusted again to 10 min, the current density is 80 mA / cm², nickel is redeposited, the deposition time is 10 min, the current density is 50 mA / cm², the laser power is set to 300 W, the spot diameter of the laser beam is 1 mm, the scanning speed is 20 mm / s, argon is selected as the shielding gas, the gas flow rate is 5 L / min, and the overlap rate of the surface remelting zone is 30%, an alloy remelting layer with a thickness of 80 μm is formed, and a uniform composite structure is obtained, and the hardness is increased to 320 HV.

[0083] The microstructure of the composite layer was observed by a transmission electron microscope. The transmission electron microscope uses an electron beam to penetrate the sample. Since the atomic arrangements of the crystal phase and the amorphous phase are different, there are differences in the electron scattering ability, resulting in different contrasts in the image, and the distribution, morphology, and size of the crystal phase and the amorphous phase and other microstructural characteristics can be clearly observed. A hardness testing device (such as a Vickers hardness tester, a nanoindentation instrument, etc.) was used to analyze the hardness of the composite layer and compare it with the substrate. The hardness test is based on the indentation principle. By applying a certain load to generate an indentation on the sample surface, the hardness value is calculated according to the size and shape of the indentation. By comparing the hardness of the composite layer and the substrate, the effect of the composite layer on improving the surface hardness of zirconium can be intuitively evaluated, and then the improvement degree of its wear resistance can be inferred. By observing and analyzing the microstructure and hardness of the composite layer, the performance of the composite layer can be deeply understood, providing a basis for optimizing the preparation process.

[0084] It is worth noting that: the high-energy laser beam generated by the laser scanning head 9 is focused by the optical system and irradiated on the surface of the zirconium material placed in the processing area. The metal deposition layer electroplated on the surface of the zirconium material quickly absorbs energy under the action of the laser energy, and the temperature rises sharply above the melting point, melting together with the surface layer of the zirconium material substrate to form a molten pool. During the formation of the molten pool, argon is continuously introduced to form a protective gas curtain around the molten pool, isolating the air to prevent oxidation and other harmful reactions. The inert gas protection cover 8 maintains a relatively stable environment in the processing area, reducing external interference. The laser beam moves on the surface of the zirconium material at the set scanning speed and path, causing the molten pool to move and solidify continuously, thereby realizing the alloying of the deposition layer and the surface layer of the zirconium material substrate. Due to the extremely high laser cooling rate, during the rapid cooling process of the molten pool, some regions meet the conditions for amorphous formation to form an amorphous phase, and the remaining parts form a crystal phase, and finally a crystal-amorphous composite layer is obtained on the surface of the zirconium material.

[0085] This application provides a specific implementation method: The metal matrix is made of industrial pure zirconium. The oxide layer on the surface of zirconium is removed by polishing, and then the polished zirconium is ultrasonically cleaned with anhydrous ethanol and deionized water respectively. The schematic diagram of the electrodeposition device is as Figure 2 shown. The electrodeposition device includes an auxiliary electrode 2, a reference electrode 3, an electrodeposition solution 4, and an electrochemical workstation 5.

[0086] By selecting different electrodeposition solutions 4 for electrodeposition on the surface of zirconium material 1, the amorphous system selected in this example is the zirconium-copper-nickel system. The electrodeposition solution includes a copper sulfate solution and a nickel sulfate solution. Among them, when depositing copper, the electrodeposition solution is the copper sulfate solution, and when depositing nickel, the electrodeposition solution is the nickel sulfate solution. First, copper is electrodeposited on the surface of zirconium material 1, and then nickel is deposited. The morphology of the deposited sample is as Figure 3 shown. Among them, Figure (a) is a surface morphology photo of the Cu coating obtained after electrodepositing Cu on the surface of zirconium, and Figure (b) is a morphology photo of the surface after electrodepositing Ni coating on the surface of zirconium after electrodepositing Cu. The laser surface alloying equipment is as Figure 4 shown. Figure 4 In it, zirconium material 2 7 is a zirconium sample piece after electrodepositing Cu and Ni on the surface. It is placed in an inert gas protection cover 8, and argon is introduced through the argon inlet pipe 6. Then, the laser scanning head 9 is moved by the laser platform control system to perform laser surface remelting to achieve surface alloying. The electrodeposited zirconium material 2 7 is placed on the laser processing platform for surface alloying treatment. The laser processing platform includes an argon inlet pipe 6, an inert gas protection cover 8, and a laser scanning head 9. The macroscopic surface morphology of the treated sample is as Figure 5 shown. It can be seen that after laser surface remelting alloying, a uniform, flat, and well-metallic-luster composite layer is formed on the surface of the zirconium sample piece. The cross-sectional microscopic morphology is as Figure 6 shown. By observing with a scanning electron microscope, it can be seen that the composite layer has good metallurgical bonding with the zirconium matrix. The thickness of the composite layer is about 100 μm, the structure inside the layer is uniform and dense, and no pores or cracks are found. It is confirmed by a transmission electron microscope that a crystal-amorphous composite layer is obtained on the surface of zirconium, as Figure 7 shown. By observing with a transmission electron microscope, it can be seen that in Figure (a), the structure of the composite layer shows a composite feature of ordered and disordered atomic arrangements, and in Figure (b), the selected area electron diffraction pattern is a diffraction pattern in a typical state of coexistence of amorphous and crystal, which proves that the composite layer is a crystal-amorphous composite structure. Hardness tests show that the hardness of the crystal-amorphous composite layer on the surface of zirconium is significantly higher than that of the matrix, and it has better wear resistance, as Figure 8 shown. Through hardness tests, it is found that the hardness of the zirconium matrix is about 140 HV, while the hardness of the composite layer is as high as about 355 HV, indicating that the method for preparing the crystal-amorphous composite layer proposed by the present invention can greatly improve the surface hardness of zirconium, so that its surface has excellent wear resistance.

[0087] It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0088] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent of the present invention shall be subject to the appended claims.

[0089] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface, characterized in that: The following steps are involved: Step S1: determining a suitable zirconium-based amorphous alloy system, and preparing an electrodeposition solution containing elemental cations of the alloy system; Step S2: pre-treating the zirconium workpiece; Step S3: connecting the pretreated zirconium workpiece with a copper wire to form a working electrode; Step S4: using an electrochemical workstation to perform electrodeposition on the surface of the zirconium workpiece to obtain a metal reduction coating; Step S5: performing laser surface alloying treatment based on the metal reduction coating to form an alloy remelting layer; Step S6: remelting the remelted layer multiple times to obtain a crystal-amorphous composite layer prepared on the zirconium surface.

2. A method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: The zirconium-based amorphous alloy system in step S1 is a zirconium-copper-nickel system, and the electrodeposition solution includes a copper sulfate solution and a nickel sulfate solution, wherein when depositing copper, the electrodeposition solution is a copper sulfate solution, and when depositing nickel, the electrodeposition solution is a nickel sulfate solution.

3. A method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: The process of obtaining a metal reduction coating comprises: Copper was first deposited for 10 min at a current density of 60 mA / cm², and then nickel was deposited for 10 min at a current density of 30 mA / cm².

4. The method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: In the step S5, before the laser surface alloying treatment, the electrodeposited zirconium workpiece is dried at a temperature of 60° C. for 30 minutes.

5. The method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: In step S5, the laser power is set to 500W, the spot diameter of the laser beam is 1mm, and the scanning speed is 10mm / s; Argon was selected as the protective gas, the gas flow rate was 5L / min, the overlap rate of the surface remelting zone was 50%, and the alloy remelting layer was formed; When the alloy remelting layer is remelted multiple times, the laser power, scanning speed, type of shielding gas and flow rate of each remelting are the same as those of the initial laser surface alloying treatment.

6. A method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: The step S2 pre-treats the zirconium workpiece by grinding and ultrasonic cleaning; Use 400#, 800#, 1200#, 1500#, and 2000# sandpaper to polish in sequence; Anhydrous ethanol and deionized water were used for ultrasonic cleaning, and the cleaning time was 2 min.

7. The method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: After the composite layer is obtained in step S6, the step also includes observing the structure and morphology of the composite layer using a transmission electron microscope, analyzing its hardness using a hardness testing device, and comparing it with the matrix.

8. The method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: In the step S1, before determining the zirconium-based amorphous alloy system, the amorphous forming ability test is performed on the candidate alloy system.

9. The method for preparing a crystalline-amorphous composite wear-resistant layer on a zirconium surface according to claim 1, characterized in that: During the electrodeposition process of step S4, the electrodeposition liquid is stirred at a stirring speed of 100 r / min.

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