Laser-assisted electro-deposition equipment in eutectic solvent and preparation method of nickel-based plating layer of laser-assisted electro-deposition equipment

Abstract

The invention discloses laser-assisted electro-deposition equipment in a deep eutectic solvent and a preparation method of a nickel-based composite coating of the laser-assisted electro-deposition equipment, and belongs to the technical field of electro-deposition and surface functional coatings. The equipment comprises a box body, a laser, an electro-deposition power supply, a three-dimensional motion platform, a control system and an auxiliary temperature control and liquid circulation module, and has a laser-current cooperative control function. Local crystal reconstruction and particle embedding in the deposition process are enhanced through the laser heat shock effect, and accurate regulation and control over electro-deposition morphology and functions are achieved. And power supply constant voltage control is combined to prepare the Ni-based protective coating. The equipment is high in structural intelligence degree and suitable for surface protection and functional coating preparation of metal matrixes in the fields of aviation, ships, energy and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrodeposition and functional surface modification, and particularly relates to a laser-assisted electrodeposition device in a deep eutectic solvent and a nickel-based composite coating prepared thereby, which is applicable to the construction of multifunctional metal surfaces. Background Art

[0002] Electrodeposition technology is a surface modification method for depositing metal or alloy coatings on the surface of a conductive substrate through an electrochemical method. Due to its advantages such as simple process, low cost, and strong controllability, it is widely used in industries such as electronics, molds, mechanical parts, aerospace, and automotive manufacturing to achieve various functions such as anti-corrosion, hardness improvement, wear resistance improvement, and conductivity enhancement. However, there are still many technical bottlenecks in the practical application of traditional electrodeposition. On the one hand, since the deposition process mostly relies on the natural progress of diffusion and reduction processes and lacks fine external regulation, problems such as many pores, large crystal grains, uneven particles, and insufficient bonding force often occur in the metal deposition layer, especially when preparing high-density and high-performance coatings. On the other hand, if functional fillers (such as ceramics, lubricants, corrosion inhibitor particles, etc.) are introduced during the deposition process, their distribution in the coating is often affected by factors such as gravitational sedimentation and interface energy mismatch, easily resulting in uneven distribution or difficulty in effectively embedding, which restricts the improvement of the performance of the composite coating.

[0003] Currently, some studies have attempted to introduce physical fields such as ultrasound, electromagnetic fields, and micro-vibration into the electrodeposition process to improve the uniformity and bonding of the coating, but problems such as non-concentrated energy action, insufficient temperature rise at the deposition interface, and poor synergy exist. Laser-assisted electrodeposition (LECD) technology, as a new composite strengthening method, can significantly improve the diffusion behavior, reduction rate, and grain reconstruction mechanism of metal ions at the electrolyte interface by introducing a laser beam to locally heat and couple the energy of the deposition cathode surface. Laser irradiation can not only increase the nucleation density and inhibit the growth of columnar crystals, but also induce physical clamping of particle embedding and interfacial reactions of the metal matrix, effectively improving the density, stability, and functional consistency of the composite deposition coating. In addition, traditional electrodeposition mostly uses water-soluble metal salt electrolytes such as sulfates and chlorides, which have problems such as high corrosivity, large environmental pollution, and strict requirements for equipment and operators. Deep eutectic solvents (DESs), especially the green DES system composed of choline chloride and ethylene glycol, have become excellent candidates to replace traditional aqueous electrolytes in recent years due to their advantages such as low toxicity, biodegradability, and high stability.

[0004] In summary, there is currently a lack of an integrated equipment system that combines laser energy field regulation, efficient reduction in the electroplating process, and a green electrolysis system. This system can deeply optimize the structure and performance of Ni-based functional coatings while ensuring environmental protection processes. The present invention precisely addresses this technical gap by proposing a laser-assisted electroplating device and method to achieve the preparation of multifunctional Ni-based composite coatings with controllable structures and excellent properties. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser-assisted electroplating device to address the problems in the prior art, such as the non-dense structure of electroplated coatings, poor surface functional stability, and insufficient environmental protection of traditional processes. Through the synergistic effect of laser and electric field, multi-scale precise regulation of the metal ion reduction process and coating structure is achieved in a green electrolyte environment, and the synergistic embedding and composite strengthening of functional fillers are realized in the Ni-based coating, thereby obtaining a high-performance composite coating with high adhesion, superhydrophobicity, and excellent corrosion resistance.

[0006] To solve the above problems, the present invention proposes the following technical solution: A laser-assisted electroplating device includes an equipment architecture integrating a pulsed laser and an electroplating system; a deep eutectic electroplating solution system based on the choline chloride-ethylene glycol system, containing NiCl 2 as the metal source. The electrolytic cell is made of transparent corrosion-resistant materials (such as acrylic, glass) to facilitate the direct penetration of the laser action path; the control system works in coordination with PLC and HMI to achieve linkage programming and feedback control of laser power, current density, scanning trajectory, and deposition time.

[0007] Preferably, as Figure 1 shown, the device runs on a computer platform through dedicated control software, and parameters such as laser power, scanning path, electroplating current density, deposition time, and electrolyte temperature can be precisely set and dynamically adjusted to facilitate workpiece installation, electrolyte replacement, and equipment maintenance operations.

[0008] Preferably, a support frame is connected to the bottom of the electrolytic cell. A three-dimensional workpiece positioning platform is provided on the support frame. A programmable stepping motor is installed at the bottom of the positioning platform, and the motor drives the platform to move along the X, Y, and Z axes through a linkage guide rail to achieve multi-angle precise positioning of the workpiece; a workpiece fixture is provided on the platform for fixing the metal substrate to be plated.

[0009] Preferably, the electrolytic cell is made of transparent acrylic or borosilicate glass materials. An anode plate is fixedly provided on the side wall of the electrolytic cell, and the anode is connected to the positive pole of a constant power supply through a wire; the cathode is the workpiece to be plated, which is connected to the negative pole of the power supply through a copper plate to form a closed electroplating circuit; a temperature-controlled circulating water jacket is provided at the lower part of the electrolytic cell and is connected to a constant temperature heating unit to maintain the electrolyte temperature stable.

[0010] Preferably, the laser is fixedly installed on the top of the box body. The laser is a Nd:YAG pulsed laser. The output end of the laser is connected to the laser scanning head through a light guiding optical fiber. The laser beam is focused on the surface of the workpiece through a transparent electrolyte after passing through the scanning galvanometer. The power of the laser is 200–500 W, and the pulse frequency is 1–200 Hz, which can be flexibly adjusted according to process requirements.

[0011] Preferably, the light guiding system includes an adjustable universal light arm and an auto-focusing lens assembly. One end of the light guiding system is connected to the laser, and the other end is vertically fixed above the inside of the box body to ensure that the laser beam can stably act on the deposition area. The system is equipped with a cooling water pipe and a splash-proof light shield to prevent the escape of laser hot spots or the interference of bubbles.

[0012] Preferably, the control system includes a PLC main control unit and an HMI touch screen interface. A display screen, a voltage / current adjustment module, a laser control knob and a data recording port are provided on the control panel. This system can realize the synchronous linkage control of laser output, electroplating power supply, platform displacement and temperature control system, and can store and export the deposition process data in real time.

[0013] Preferably, the electrolytic cell is connected to the power supply through a copper plate and is provided with a plurality of functional interfaces, including a USB debugging port, a power switch, cooling water inlet and outlet, and a laser safety plug lock. All electrical modules are provided with grounding protection and overload open circuit protection devices to ensure the safety of operators.

[0014] Compared with the prior art, the significant advantages of the present invention are reflected in the following aspects: 1. The present invention uses a laser beam to locally irradiate the cathode surface area, introducing a controlled heat input during the deposition process, causing the local temperature of the deposition area to rise instantaneously, inducing the rapid reduction of Ni²⁺ and promoting multi-point nucleation of crystal nuclei, avoiding the problems of coarse grains and disordered directions in conventional electroplating. The laser thermal field simultaneously softens the surface layer of the workpiece, improves the plastic embedding ability of Ni crystals, enhances the metallurgical bonding strength between the coating and the substrate, and finally realizes a high-quality Ni coating that is dense and pore-free.

[0015] 2. In the laser-assisted deposition environment, functional enhanced particles (such as tungsten carbide WC, titanium carbide TiC, molybdenum disulfide MoS 2 etc.) are induced by laser radiation to form a directional migration trend in the high-temperature area and co-deposit with the newly formed Ni crystals. The laser field effectively reduces particle agglomeration and interfacial tension, enabling them to form a composite structure of "heat-induced embedding + co-crystallization fixation" in the Ni matrix. This mechanism has more structural stability and long-term functional retention ability compared to physical coating or simple mixing.

[0016] 3. The choline chloride-ethylene glycol (ChCl–EG) system used is a typical low-toxic and biodegradable deep eutectic solvent, which has good Ni²⁺ conductivity, a wide electrochemical window, and thermal stability. Compared with the traditional sulfate- and ammonia-containing systems, the electrolyte of the present invention can operate stably under low-voltage conditions without generating gas pollution or corrosive by-products, greatly improving operational safety and environmental friendliness, and is suitable for large-scale popularization and application. Description of the Drawings

[0017] Figure 1 This is a schematic diagram of the overall structure of the laser-assisted electrodeposition equipment described in the present invention. The figure shows the main constituent units of the equipment, including a laser, a light guiding system, an electrolytic cell, a power supply system, a workpiece positioning platform, a temperature control and circulation module, and a PLC control system, and shows the process of the laser beam acting on the cathode surface and the layout of the electrodeposition circuit.

[0018] Figure 2 This is a schematic diagram of the structure of the transparent electrolytic cell.

[0019] Figure 3 This is a scanning electron microscope (SEM) image of the surface of the Ni-based coating obtained under the process conditions of conventional electrodeposition (ECD).

[0020] Figure 4 This is a SEM image of the surface of the Ni-based composite coating obtained by laser-assisted electrodeposition (LECD) under the condition of a laser power of 300 W.

[0021] Figure 5 This is a three-dimensional topography map of the coating surface under different laser power conditions Figure 6 This is a polarization curve graph of each sample (Al, ECD, LECD-300) in a 3.5 wt.% NaCl solution.

[0022] Figure 7 This is a polarization curve graph of samples (200 - 500 W) with different laser powers in a 3.5 wt.% NaCl solution. Specific Embodiment

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings of the specification.

[0024] Observation of surface topography: Use a scanning electron microscope (SEM) to observe the microscopic topography of the surfaces of electrodeposited and laser-assisted electrodeposited samples.

[0025] Electrochemical tests: The polarization curves (Tafel) of the coatings were tested using an IVIUM electrochemical workstation (Netherlands). A three-electrode system was used for the tests. The sample piece was the working electrode, the auxiliary electrode was a platinum electrode, and the reference electrode was a saturated calomel electrode. The corrosive medium was a 3.5% (mass fraction) NaCl solution, and the test environment was (25 ± 2) °C. During EIS testing, the measurement frequency was from 0.01 Hz to 100 kHz, and the sine wave amplitude was 10 mV. The scanning rate of the potentiodynamic polarization curve was set at 10 mV / s. To ensure the reliability of the test results, at least three tests were conducted at different sample points under each test condition.

[0026] Three-dimensional morphology: The three-dimensional profiles of different sample surfaces were observed using a laser confocal microscope (KC-X1000). The surface flatness and surface roughness at different laser powers were compared.

[0027] As Figure 1 and Figure 2 shown, a laser-assisted electrodeposition device includes an electrolytic cell provided with an electronic control interface area. By connecting to an external computer control system, full automation control of the operation of the whole machine is achieved. The computer system is pre-installed with the control software developed by the present invention, and parameters such as laser power, current density, deposition time, laser path, and electrolyte temperature can be set and monitored in real time.

[0028] The electrolytic cell is made of acrylic or borosilicate glass and contains a Ni anode plate disposed near the cell wall and connected to the positive pole of the power supply through a wire. The cathode is the metal workpiece to be electroplated, which is fixed on the platform by a copper plate fixture and connected to the negative pole of the power supply to construct an electrodeposition circuit. The workpiece platform is installed on a three-dimensional motion mechanism and driven by a stepping motor to achieve precise positioning of the workpiece in the X, Y, and Z directions.

[0029] The electrodeposition liquid is a choline chloride-ethylene glycol deep eutectic solution system with a mass ratio of 1:2, containing 0.2 mol / L NiCl 2 as the metal source. The electrolyte temperature is maintained at 40 °C, and a constant temperature cycle is achieved using a heating module and a circulation pump system. The control system sets the electrodeposition potential at 1.5 V and the deposition time at 10 minutes through the computer interface. Examples

[0030] (1) Preparation of the deep eutectic electrolyte. Weigh 112.5 g of choline chloride and place it in a beaker. Slowly add 90 mL of ethylene glycol solution measured with a measuring cylinder. Place the mixture on a magnetic stirrer at 70 °C and stir for 2 h until it is completely dissolved and the solution becomes colorless and transparent, obtaining a choline chloride-ethylene glycol deep eutectic solution with a mass ratio of 1:2; (2) Add 9.56 g of nickel chloride to the above DES solution, continue to stir well at 70 °C until completely dissolved, place it in an electrolytic cell, polish and activate the sample Al to be plated and then place it in the solution, control the electrodeposition time to 10 min; the laser scanning interval is 0.03 mm, and the depth of the workpiece sinking into the liquid surface is controlled to 1 mm.

[0031] (3) Use a Nd:YAG pulsed laser, set the output power to 200 W, 300 W, 400 W, and 500 W respectively, control the scanning speed at 300 mm / s, and synchronously act on the workpiece surface during the assisted electrodeposition process to obtain Ni-based protective coatings with different degrees (named LECD-200, LECD-300, LECD-400, and LECD-500 respectively). The surface structure is as Figure 3 shown. The electroplated particles are more uniform, have a better combination with the substrate, and form a strengthening phase.

[0032] The three-dimensional surface topography structure of the sample is as Figure 5 shown. With the increase of the laser power in the laser-assisted electrodeposition (LECD) sample, its surface microstructure tends to be regular and more dense. Especially under the condition of 300 W laser power (LECD-300), the coating surface is more uniform, indicating that the thermal field input and the crystal nucleation / growth behavior reach a good matching state under this laser parameter. When the laser power continues to increase to 400 W and 500 W, although the coating surface still has a certain flatness, there are characteristics such as blurred local melting boundaries and slightly piled-up tissues, and the surface roughness becomes larger. Excessive laser power causes an increase in surface recrystallization distortion or overheated areas, affecting the orderliness of the microstructure.

[0033] The working principle is as follows: During the electrodeposition process, Ni²⁺ is reduced on the surface of the cathode workpiece, and at the same time, the laser beam irradiates the workpiece synchronously, forming a local thermal field to induce the directional growth of grains and the co-deposition of ceramic particles. Within the adjustable range of the laser power, the energy input balances the particle migration, crystallization rate, and interfacial bonding strength.

[0034] Comparative example To verify the role of the laser-assisted mechanism by comparison, use the same electrodeposition system and parameters as in the above examples, without introducing laser irradiation, that is, perform electrodeposition treatment on the sample without applying laser, and the obtained coating is used as the control group (conventional electrodeposition, ECD). The surface structure is as Figure 4 shown. The electroplated particles fail to completely cover the surface of the sample, and there is still a large area of the substrate exposed, which has a great impact on the performance of the coating.

[0035] Perform Tafel corrosion tests on the protective coatings obtained in the examples and comparative examples, as Figure 6 and Figure 7As shown, the conventional electro-deposited sample (ECD) has certain improvement compared to the substrate, but shows a lower corrosion potential and a larger corrosion current density compared to the laser-assisted electro-deposited sample, indicating that it is prone to rapid electrochemical corrosion in a chloride ion environment; in the laser-assisted electro-deposited sample (LECD), as the laser power increases, the corrosion current density gradually decreases and the corrosion potential shifts relatively positively, indicating that the laser thermal field effect helps to improve the coating densification and interface stability; for the LECD-400 and 500 samples, due to the high-power conditions, local overheating, uneven sintering and other phenomena occur on the coating surface, resulting in slightly fluctuating performance.

[0036] Comprehensive analysis shows that the laser-assisted electro-deposition technology realizes the microstructure ordering and performance leap of the Ni-based composite coating through local laser thermal field regulation, and is suitable for constructing functional coatings.

Claims

1. A laser-assisted electrodeposition device and a method for preparing a nickel-based composite coating, characterized in that: It includes a laser, an electrodeposition power supply, a control system, a three-dimensional workpiece positioning platform, an electrolytic cell and a temperature control circulation system; the electrolytic cell contains a Ni²⁺ DES solution system, the laser synchronously irradiates the surface of the metal workpiece to be plated through a light guide module, and induces local thermal effects and surface melting reconstruction during the deposition process. The power output end is connected to the workpiece, the workpiece is placed in the solution as a cathode, and the anode is connected to the power supply. The synchronous linkage control of the laser and the current can be achieved through the control system.

2. The device according to claim 1, characterized in that The laser is one or more of a nanosecond pulse laser, a picosecond laser, a femtosecond laser, and a carbon dioxide laser, with adjustable wavelength, power, and scanning mode, and can achieve precise control of the thermal field and tissue refinement in the electrodeposition area.

3. The device according to claim 1 or 2, characterized in that The control system includes an automatic control module, which can realize the real-time linkage setting of multiple parameters such as laser scanning path, power parameters, on-off timing, current density, deposition time, etc. and the data recording and analysis of the deposition process.

4. The device according to claim 1, characterized in that The electrolytic cell is made of acrylic plate, glass or other light-transmitting materials. The anode is close to the inner wall and connected to the positive pole of the power supply through a conductive wire. The cathode is the workpiece to be plated, which is placed inside the solution and connected to the negative pole of the power supply through a highly conductive copper plate or copper wire to form an electrodeposition circuit.

5. The device according to claims 1-4, characterized in that The electrolyte contains Ni + The metal ion source includes one or more of nickel chloride, nickel sulfate, and nickel nitrate, with a concentration of 0.1-0.3 mol / L.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the choline chloride and hydrogen bond donor deep eutectic solution system is 1:2 or 1:3; the hydrogen bond donor is one or more of urea, ethylene glycol and thiourea; the dissolving temperature is heated at 80-120°C for 30-2h.

7. The method for preparing the device or coating according to claim 1, characterized in that The workpiece substrate described in the steps is one or more of iron, aluminum, copper, magnesium, titanium or alloys, the treatment is grinding, surface decontamination and drying, and the anode is one of nickel sheet, graphite or conductive material.

8. The Ni-based composite coating prepared by the equipment according to claim 1, characterized in that: The coating is composed of a Ni metal layer formed by laser-assisted electrodeposition, in which high-hardness and corrosion-resistant ceramic particles such as tungsten carbide (WC), titanium carbide (TiC), and molybdenum disulfide (MoS2) are uniformly dispersed.

9. The device or coating according to claim 1, characterized in that The laser-assisted electrodeposition process uses a power source range of one of direct current, alternating current or pulsed power supply, a deposition time range of 5-20 min, and a deposition voltage of 1-2.5 V; the laser-assisted electrodeposition process uses a laser power range of 200-500 W, and a scanning speed adjustment range of 100-1000 mm / s; the depth of the workpiece surface from the liquid surface is set to 0.5-2 mm, and the scanning interval is 0.01-0.1 mm.

10. The laser-assisted electrodeposition method according to any one of claims 1 to 8, characterized in that: By adopting a laser synchronous assisted mechanism and adjusting the coupling timing of laser heat input and electrochemical reduction reaction, the dynamic induction of Ni²⁺ deposition process is realized in the choline chloride-ethylene glycol deep eutectic liquid system, which significantly improves the microstructure uniformity and metal-matrix bonding ability of the coating, while giving the prepared coating multi-scale protective performance.

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