System and method for rapidly preparing low-surface-energy self-cleaning metal component through combination of laser additive manufacturing and laser etching

Abstract

The invention provides a system and method for rapidly preparing a low-surface-energy self-cleaning metal component through laser additive manufacturing and laser etching, and the method comprises the steps that when a target component is obtained in the additive manufacturing process, metal wires are melted and stacked layer by layer in a laser additive mode, and a component base body is obtained; and when printing to the outer surface of the component, increasing the laser frequency, and performing laser etching on the outer-layer metal, so that the surface part of the metal is subjected to evaporation or stripping reaction, and a surface micro-nano structure is etched. And through the combined action of laser material increase and laser etching, the printed metal component has the characteristic of low surface energy, and the self-cleaning capacity is improved. And the printed metal component is further subjected to ultrasonic fluorination low-surface-energy substance modification treatment, the surface hydrophobicity of the component is enhanced, the surface water contact angle of the component is larger than 160 degrees, the self-cleaning, anti-corrosion, anti-icing and anti-frost capacity of the metal component is enhanced, the component can adapt to the deep sea working environment, and the service life of the metal component is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium alloy additive manufacturing, in particular to a high-performance self-cleaning titanium alloy material for deep-sea engineering, and more particularly to a system and method for laser additive manufacturing and composite laser etching for rapidly preparing a low-surface-energy self-cleaning metal component. BACKGROUND

[0002] With the continuous development of global ocean exploration, there is an urgent strategic demand for deep-sea equipment serving in extreme environments. The performance and reliability of deep-sea engineering equipment have become key factors affecting deep-sea resource exploration and development, scientific experiments, and territorial security and rights, especially the development of materials serving in extreme deep-sea environments. In the field of deep-sea engineering such as new-generation ships, submersibles, deep-sea pipelines, and ocean research devices, titanium alloys have become key structural materials due to their high strength, corrosion resistance, and low density. However, the deep-sea environment has characteristics such as high salt, high pressure, low temperature, and complex marine bioattachment, which puts high requirements on the surface properties of titanium alloy components. Low surface energy characteristics can effectively reduce marine bioattachment, and self-cleaning function can ensure that the component surface remains in good working condition for a long time, avoiding problems such as accelerated corrosion, increased resistance, and increased energy consumption caused by bioattachment. Currently, traditional titanium alloy component preparation methods cannot achieve uniform and stable low surface energy and self-cleaning properties on the surface of complex-shaped components, which cannot meet the long-term reliable service requirements of deep-sea engineering components.

[0003] Currently, methods for preparing low-surface-energy self-cleaning structural materials mainly include coating, chemical etching, laser processing, and acid etching. Laser processing is widely used in the manufacturing of micro-nano structures on metal surfaces due to its high repeatability, high processing efficiency, and no pollution. Traditional coating methods have problems such as insufficient adhesion between the coating and the substrate, poor weather resistance, and easy peeling and failure in deep-sea high-pressure and highly corrosive environments. Chemical etching methods are complex and have low controllability, making it difficult to accurately process the surface of complex three-dimensional components, and may cause environmental pollution. Currently, laser additive manufacturing technology can achieve near-net shaping of complex-shaped titanium alloy components, but single laser additive manufacturing technology cannot directly impart low-surface-energy self-cleaning properties to the components. SUMMARY

[0004] To address the shortcomings and deficiencies of existing technologies, this invention aims to provide a method for rapidly preparing low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching. This method involves simultaneously printing titanium alloy components onto a substrate using laser additive manufacturing, while simultaneously etching the outer metal layer by changing the laser processing direction and controlling the laser frequency. This etches micro / nano structures onto the outer surface of the component. The printed metal component is then modified with an ultrasonically fluorinated low surface energy material, resulting in a highly electronegative, low atomic radius fluoride ion layer. This rapidly yields a superhydrophobic, self-cleaning metal component, improving the metal surface's corrosion resistance, self-cleaning properties, and anti-icing and anti-fogging functionality.

[0005] According to a first aspect of the present invention, a system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching is provided, comprising:

[0006] Forming base plate;

[0007] A molding cylinder located below the molding substrate, supporting the molding substrate and capable of driving it to move in a vertical direction;

[0008] A rotary drive device for driving the molding cylinder and the molding substrate to rotate synchronously in the horizontal direction.

[0009] Wire feeder, used to transport metal wires for additive manufacturing;

[0010] A laser cladding head is used to perform laser cladding on a conveyed metal wire using a first process parameter, move along a planned path and deposit components on the surface of the substrate in a layer-by-layer manner; and to perform laser etching on the peripheral outer surface of every n deposited layers using a second process parameter, where n is a positive integer greater than or equal to 1.

[0011] The laser cladding head is mounted on the spindle of a CNC machining center or the robotic arm of a multi-axis robot, so that it can be driven by the spindle or robotic arm to move along a planned path to perform laser cladding. After being driven to deflect around the deposition layer, it performs laser etching on the peripheral outer surface of the deposition layer to form a surface micro-nano protrusion structure on the peripheral outer surface.

[0012] According to a second aspect of the present invention, a method for rapidly preparing low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching is provided, comprising the following steps:

[0013] Step S1: Using metal wire as raw material, the laser cladding additive manufacturing process is adopted. Based on the single-layer deposition thickness of the metal component slice and the planned path, the metal additive deposition is carried out on the molding substrate from the first layer in a bottom-up, layer-by-layer manner until the printing of the entire metal component is completed.

[0014] In the printing process, starting from the first layer, for each n deposited layer obtained by printing, the laser power, angle, scanning path and the direction of the substrate of the laser cladding head are adjusted to perform laser etching on the peripheral outer surface of each n deposited layer to obtain surface micro-nano protrusion structures, where n is a positive integer greater than or equal to 1.

[0015] Step S2: Laser etching is performed on the upper surface of the metal component to form a surface micro-nano protrusion structure on the upper surface;

[0016] Step S3: Heat-treat the metal component with surface micro / nano protrusions.

[0017] Step S4: Modify the heat-treated metal component with an ultrasonically fluorinated low surface energy material. The fluorinated groups are attached to the surface of the micro-nano protrusion structure by ultrasonic assistance, so that the water contact angle of the component surface exceeds 160°.

[0018] The metal wire is selected from titanium alloy, steel or aluminum alloy.

[0019] Compared with existing technologies, the significant advantages of the method for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching proposed in this invention are as follows:

[0020] 1. This invention proposes a method for achieving self-cleaning of component surfaces by printing low surface energy metals through laser additive manufacturing. After laser additive manufacturing of aluminum alloy and titanium alloy wires, nanosecond laser processing is used to construct and etch micro-nano protrusion structures. Low surface energy modification is achieved through fluorination treatment, and wettability is measured by contact angle. Thus, low surface energy modification of the metal surface is achieved simultaneously with additive manufacturing. Combined with ultrasonic fluorination treatment, superhydrophobic properties of the metal surface are achieved.

[0021] 2. Compared with traditional processes, this invention performs laser etching simultaneously with additive manufacturing, combined with subsequent heat treatment to protect the surface micro-protrusion structure and ultrasonic fluorination treatment, which can quickly obtain superhydrophobic metal components. This method can be widely applied to various metal materials, enabling the metal material surface to achieve a highly durable superhydrophobic surface, which helps to improve the metal surface's corrosion resistance, self-cleaning properties, and anti-icing and anti-fogging functions. It can greatly improve the efficiency of modifying low surface energy metals, quickly achieve superhydrophobic metal surfaces, and significantly improve production efficiency in actual production.

[0022] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure.

[0023] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0024] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the process flow for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching, according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the rotating structure of the molding cylinder and the molding substrate according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of a laser-etched surface micro / nano protrusion structure according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the surface microstructure and hydrophobicity of the component after additive etching. Detailed Implementation

[0029] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0030] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0031] {Example 1}

[0032] Combination Figures 1-4 As shown, the system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to an embodiment of the present invention combines laser additive manufacturing (LAM) with simultaneous laser etching, thus creating low surface energy metal components with self-cleaning capabilities. Figure 1 The system design shown includes a molding substrate 10, a wire feeder 20, a laser cladding head 30, a molding cylinder 40, an arc-shaped guide rail 50, and a rotary drive device 60.

[0033] Combination Figure 1 , 2 As shown, the molding cylinder 40 can be a hydraulic cylinder structure, located below the molding substrate 10, supporting the molding substrate 10, and driving the molding substrate 10 to move in the vertical direction by the movement of the piston rod. Thus, in the additive manufacturing process, it can descend layer by layer as the printing process progresses (according to the thickness d of each deposition layer), so that the deposition layer on its surface can be deposited and shaped in a layer-by-layer upward growth direction until a complete metal component is obtained.

[0034] Combination Figure 1 , 2 As shown, the rotary drive device 60 preferably adopts a rotary motor drive structure. The rotation output of the drive motor drives the molding cylinder 40 and the molding substrate 10 to rotate synchronously in the horizontal direction via a transmission mechanism, so that the deposited layer on the surface of the molding substrate 10 rotates synchronously around the central axis of the molding cylinder 40. Preferably, the drive motor is a stepper motor to ensure high precision and controllability of the rotation process.

[0035] Wire feeder 20 is used to feed metal wire 100 for additive manufacturing. Metal wire 100 is selected from titanium alloy, steel or aluminum alloy.

[0036] The laser cladding head 30 is preferably integrated with the wire feeder 10 to deliver metal wire 100 to the surface of the forming substrate 10 via coaxial or off-axis wire feeding.

[0037] Combination Figure 1 As shown, the laser cladding head 30 is designed to perform laser cladding on the conveyed metal wire using a first process parameter, move along a planned path and deposit components on the surface of the substrate in a layer-by-layer manner; and to perform laser etching on the peripheral outer surface of every n deposited layers using a second process parameter, where n is a positive integer greater than or equal to 1.

[0038] In embodiments of the present invention, the laser cladding head 30 can be mounted on the spindle of a CNC machining center or the robotic arm of a multi-axis robot, enabling it to be driven by the spindle or robotic arm to move along a planned path for laser cladding processing; and after being driven to deflect around the deposition layer, it can perform laser etching towards the peripheral outer surface of the deposition layer, forming surface micro / nano protrusion structures on the peripheral outer surface, such as... Figure 3 , 4 As shown, the obtained surface micro-nano protrusion structure is a lotus leaf papilla structure.

[0039] Therefore, in the additive manufacturing process, when obtaining the target component, laser additive manufacturing is used to melt and deposit metal wires layer by layer to obtain the component substrate. When printing onto the outer surface of the component, the laser frequency is increased to perform laser etching on the outer metal layer, causing evaporation or peeling reactions on the metal surface and etching out surface micro-nano structures. Through the combined effect of laser additive manufacturing and laser etching, the printed metal component has low surface energy characteristics, improving its self-cleaning ability.

[0040] As will be described in the embodiments, the printed metal components can be further modified with ultrasonic fluorination of low surface energy materials to cover the surface with a layer of fluoride ions with high electronegativity and low atomic radius. Fluoride groups (such as -CF3, -CF2-) are attached to the etched papillary structure by ultrasonic energy, which further enhances the hydrophobicity of the component surface, making the water contact angle of the component surface >160°. This significantly enhances the self-cleaning, corrosion resistance, and anti-icing and anti-frost capabilities of the metal components, enabling the components to adapt to deep-sea working environments and improving the service life of the metal components.

[0041] As an optional embodiment, combined with Figure 1 As shown, laser cladding and laser etching are performed using the same laser cladding head, and laser processing control is achieved by switching between a first process parameter and a second process parameter. The laser cladding head uses a fiber laser, such as a CO2 laser emitter.

[0042] As an optional embodiment, the first process parameters for laser cladding include:

[0043] The laser power range is 100–400W, the scanning speed is 500–2000 mm / s, the spot diameter is 50–100 μm, the preset printing layer thickness is 20–100 μm, the scanning strategy is checkerboard partition printing, and argon is used as the protective gas.

[0044] In the specific additive manufacturing process, specific process parameters can be selected according to the type of additive metal material, and the printing program can be set accordingly to print and form metal components.

[0045] As an optional embodiment, the second process parameters for laser etching include:

[0046] The laser power is 20-300W, the scanning speed is 300-3000mm / s, the pulse frequency is 20-100kHz, the spot diameter is 30-100μm, the defocusing amount is +0.2--0.5mm, the number of scans is 1-6, and the fill spacing spot is 50-90%.

[0047] It should be understood that the second process parameters for laser etching can be selected according to the actual type of additive etching metal material.

[0048] like Figure 1 , 3 As shown, the arc-shaped guide rail 50 is optionally mounted on the spindle or robotic arm, and the laser cladding head 30 is mounted on the arc-shaped guide rail and can be driven to move along the path defined by the arc-shaped guide rail, so that the laser cladding head can deflect around the deposition layer and perform laser etching towards the circumferential outer side of the deposition layer.

[0049] As an optional embodiment, the arc-shaped guide rail 50 is designed as a support structure, extending from directly above the molding substrate 10 toward its side, and extending to the same initial height as the molding substrate in at least one direction. Thus, combining the horizontal rotation of the molding substrate with the arc-shaped guide rail design, the laser cladding head 30 can adjust its etching angle, and the molding substrate can be rotated 360° to achieve full-angle etching on the circumferential side, eliminating dead angles in additive etching.

[0050] Combination Figure 1 As shown, in an embodiment of the present invention, the laser cladding head is also configured to perform laser etching on the upper surface of the component after the deposition of the entire metal component is completed, forming a surface micro-nano protrusion structure, namely a lotus leaf papilla structure, on the upper surface.

[0051] {Example 2}

[0052] Combination Figures 1-4 As shown, based on the aforementioned design of a laser additive manufacturing composite laser etching processing system, this embodiment proposes a method for preparing low surface energy self-cleaning metal components using laser additive manufacturing composite laser etching, comprising the following steps:

[0053] Step S1: Using metal wire as raw material, the laser cladding additive manufacturing process is adopted. Based on the single-layer deposition thickness of the metal component slice and the planned path, the metal additive deposition is carried out on the molding substrate from the first layer in a bottom-up, layer-by-layer manner until the printing of the entire metal component is completed.

[0054] In the printing process, starting from the first layer, for each n deposited layer obtained by printing, the laser power, angle, scanning path and the direction of the substrate of the laser cladding head are adjusted to perform laser etching on the peripheral outer surface of each n deposited layer to obtain surface micro-nano protrusion structures, where n is a positive integer greater than or equal to 1.

[0055] Step S2: Laser etching is performed on the upper surface of the metal component to form a surface micro-nano protrusion structure on the upper surface;

[0056] Step S3: Heat-treat the metal component with surface micro / nano protrusions.

[0057] Step S4: Modify the heat-treated metal component with an ultrasonically fluorinated low surface energy material. The fluorinated groups are attached to the surface of the micro-nano protrusion structure by ultrasonic assistance, so that the water contact angle of the component surface exceeds 160°.

[0058] {Example 3}

[0059] As a concrete example, combined Figure 1 , 2 As shown in Figure 3, we further elaborate on the specific implementation of the aforementioned method for preparing low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching. The laser cladding head uses a fiber laser with a CO2 laser emitter. The metal wire is made of titanium alloy.

[0060] (1) Preparation of raw materials: TC4 titanium alloy wire is pretreated by removing surface oil with alcohol and preheating to 200-400℃ to avoid affecting the additive manufacturing process; TC4 titanium alloy metal wire with a diameter of 0.3mm is placed in a vacuum environment at 120℃ for 2h to remove moisture and is ready for additive manufacturing.

[0061] (2) Laser preparation: An SLM Solutions NXG XII 600 CO2 laser emitter was used, with a maximum output power of 400W, an output range of 10–400W, an output laser wavelength of 1064nm, and a laser focal length of 250mm. To obtain a smooth and continuous morphology, continuous laser mode was used during the deposition process. Because the metal wire was thin, the defocusing rate of the CO2 laser emitter was adjusted to -2mm. To facilitate subsequent laser etching angle adjustment, the laser processing head was fixed to the slider and engaged with the arc-shaped bracket, and the laser processing head was fixed with positioning pins.

[0062] (3) Substrate preparation: The substrate is sanded with wet sandpaper to remove surface oxides, and then cleaned with alcohol or acetone to remove surface oil and impurities for later use. To facilitate adjustment of the etching angle, the substrate is fixed to the top of the forming cylinder for support. The bottom of the forming cylinder is driven by a rotary motor and can rotate 360°. With the help of the arc-shaped bracket, dead angles in additive etching can be eliminated. To ensure better adhesion between the deposited layer and the substrate and to eliminate uneven stress distribution during the printing process, the substrate is preheated, and modules are preheated at areas where stress tends to accumulate. The preheating temperature is controlled between 200 and 500°C according to the material's process requirements.

[0063] (4) Inert gas protection: Argon gas is introduced into the atmosphere chamber as a protective gas, and the chamber pressure is maintained at about 300 MPa to prevent the titanium alloy from oxidizing in a high-temperature environment.

[0064] (5) Metal additive stage: The TC4 titanium alloy wire prepared in step 1 is used as raw material. The wire is fed out at a speed of 180 mm / min through the wire feeder. The laser power is set to 125W and the moving speed is 120 mm / min. Under the irradiation of the laser, the metal wire undergoes violent plastic flow and dynamic recrystallization, thereby improving the microstructure of the material. At the same time, it is stacked layer by layer until the printing is completed to obtain a deposition layer with a height of about 180 μm and a width of about 750 μm.

[0065] In an optional example, at this stage, a small-batch trial can be conducted first, and the test pieces can be analyzed in detail according to the actual situation. For example, the desired microstructure can be obtained by observing and analyzing the microstructure of the test pieces, and the key process parameters in the additive manufacturing process can be adjusted according to the analysis results to obtain the optimal printing parameters.

[0066] (6) Laser Etching Stage: In the additive manufacturing stage, after each n-layer deposition process is completed (preferably 1-2 layers), the required process parameters for laser etching are set: scanning speed 500 mm / s, spot diameter 30 μm, maximum output power 60 W, laser pulse width 275 fs, and a grid-like scanning path. This increases the laser frequency to meet the requirements for laser etching, and laser etching is performed on the circumferential side surface of the component. This raises the side temperature of the deposited metal body, causing some surface metal to evaporate or peel off, increasing the surface roughness and initially obtaining the surface micro / nano structure. Specifically, the circumferential side surface of the component is etched by moving the laser processing head on the arc-shaped support in conjunction with the rotation of the forming substrate.

[0067] Given that the laser etching requires a high laser frequency, the material is heated rapidly, avoiding preferential melting of melting point components that would lead to uneven composition, inhibiting grain growth, and obtaining an ultrafine grain structure (grain size <10μm), thereby improving the material strength.

[0068] Meanwhile, the high-frequency laser of laser etching can keep the temperature of the material's surrounding area at 600°C, maintain the material's viscosity, and keep the layer-to-layer bonding force at a high level when printing the next layer of additive manufacturing.

[0069] (7) Post-processing: The printed finished metal components are subjected to stress relief treatment, hot isostatic pressing treatment, solution heat treatment and other methods. Different heat treatment methods are adopted according to different materials to optimize the microstructure and strengthen the interface bonding strength.

[0070] (8) Modification with low surface energy materials: The post-treated component is placed in a fluorination solution. Perfluorotrimethoxysilane is dissolved in ethanol solution and ultrasonically fluorinated for 10-15 minutes with ultrasonic assistance. After fluorination, it is dried at 80°C for 3 hours. The ultrasonic frequency is controlled at 60Hz. The ultrasonic energy is used to attach fluorinated groups (such as -CF3, -CF2-) to the papillary structure etched in step 5, further enhancing the hydrophobicity of the component surface and making the water contact angle of the component surface >160°.

[0071] Therefore, through the above-mentioned process, combined with laser additive manufacturing and simultaneous laser etching, the heat generated by the laser additive process melts the powder, allowing it to be deposited layer by layer to obtain the desired component. Simultaneously, the laser frequency is switched to etch the circumferential surface of the deposited layer, printing out a metal additive component with a micro / nano structure. After heat treatment to enhance the microstructure, the component is placed in a fluorination solution for 15 minutes to strengthen the surface micro / nano protrusion structure, thereby manufacturing a metal component with low surface energy.

[0072] In an optional embodiment, the upper surface of the printed component is further laser-etched before heat treatment to obtain a surface micro / nano structure.

[0073] Example 1: Preparation of titanium alloy components

[0074] (1) Take a titanium alloy wire of Ti-6Al-4V with a diameter of 0.3mm (containing 6% Al, 4% V and the remainder Ti), dry it for later use, then remove the surface oil with alcohol and install it on the wire feeder.

[0075] (2) Start the printing system and feed the filament at a speed of 180 mm / min using the friction generated by clamping. Adjust the filament alignment or spacing using a fine-tuning machine to control the appropriate deposition position. Set the process parameters and printing path: laser power range of 125W, advance speed of 120 mm / s, filament feed ratio of 1.5, to obtain a fused deposition layer with a height of approximately 180 μm and a width of approximately 750 μm, using argon as the protective gas, preheating temperature of 400℃, and laser energy density of 100 J / mm². 3 Metal components are deposited and printed layer by layer according to the preset path and interlayer thickness.

[0076] (3) Laser etching is performed simultaneously with step 2. When one layer is printed in step 2, the etching process parameters are switched to: laser power of 60W, scanning speed of 500mm / s, pulse frequency of 100kHz, laser pulse width of 275fs, spot diameter of 30μm, number of scans of 16, and scanning path of grid. The laser processing head is slid to the side along the arc-shaped guide rail, and in conjunction with the rotation of the forming substrate, the side of the component is continuously etched to obtain a nipple-like protrusion structure, thereby reducing surface energy.

[0077] (4) Continue printing and etching layer by layer in steps 2 and 3 above until the entire metal component is formed. Etch the upper surface of the prepared component to obtain a papillary protrusion structure on the upper surface, thereby reducing the surface energy.

[0078] (5) Perform hot isostatic pressing treatment, and keep it at 980℃ and 200MPa for 3 hours to make the metal interface more compact, while reducing porosity and enhancing the interfacial bonding strength.

[0079] (6) The prepared Ti6Al4V component was placed in a fluorination solution (perfluorotrimethoxysilane dissolved in ethanol solution), and the ultrasonic frequency was controlled at 60 Hz. The ultrasonic fluorination was performed for 20 minutes to attach low surface energy fluorinated groups to the etched papillary structure. After fluorination, the component was taken out and dried in an environment of 60°C for 3 hours to further enhance the hydrophobicity of the component surface.

[0080] Example 2: Fabrication of 316L stainless steel components

[0081] (1) Select 316L stainless steel wire with a diameter of 0.3mm for drying and then remove the surface oil stains with alcohol and fix it on the wire feeder. Select a defocusing amount of -2mm and a wire feeding direction of 45° in the front. Leave a wire offset of 0.1mm when wrapping the wire. Set the laser power to 160W.

[0082] (2) Start the printing system and feed the filament at a speed of 120 mm / min by relying on the friction generated by clamping. Adjust the filament alignment or filament spacing through the fine-tuning machine to control the appropriate deposition position. Set the process parameters and printing path: laser power range of 160W, forward speed of 120 mm / s, filament feed ratio of 1.5, to obtain a deposition layer with a height of about 200 μm and a width of about 620 μm, argon gas is used as the protective gas, and the preheating temperature is 400℃.

[0083] (3) Laser etching is performed simultaneously with step 2. When one layer is printed in step 2, the etching process parameters are switched to: laser power of 60W, scanning speed of 1980mm / s, laser pulse width of 240fs, spot diameter of 50μm, number of scans of 16, and scanning path of grid. The laser processing head is slid to the side along the arc-shaped guide rail, and in conjunction with the rotation of the forming substrate, the side of the component is continuously etched to obtain a nipple-like protrusion structure, thereby reducing surface energy.

[0084] (4) Continue printing and etching layer by layer in steps 2 and 3 above until the entire metal component is formed. Etch the upper surface of the prepared component to obtain a papillary protrusion structure on the upper surface, thereby reducing the surface energy.

[0085] (5) The prepared parts are subjected to hot isostatic pressing treatment at 1120℃ and 150MPa for 3 hours to make the metal interface more compact, reduce porosity and enhance the interface bonding strength.

[0086] (6) The prepared 326L alloy block was placed in the fluorination treatment solution, and the ultrasonic frequency was controlled at 60Hz. Ultrasonic fluorination treatment was carried out for 15 minutes to attach low surface energy fluorinated groups to the etched papillary structure. After fluorination treatment, it was taken out and placed in the air to dry for 3 hours to further enhance the surface hydrophobicity of the component.

[0087] {Example 4}

[0088] To test the self-cleaning performance of low surface energy metal components rapidly fabricated by laser additive manufacturing combined with laser etching, the target components obtained by this additive etching method are experimentally tested, with a metal component made of TC4 titanium alloy wire as an example.

[0089] 1. Room temperature corrosion resistance test

[0090] To simulate a marine environment, a 3.5% NaCl solution was used as the etching solution, and objects of the same size (3 cm) were subjected to etching. 3 A standard Ti6Al4V alloy block and a low surface energy titanium alloy block prepared by additive synchronous composite etching according to the present invention were placed in an autoclave. The sample to be tested was fixed with a clamp and immersed in the solution. The test temperature was 25°C and the test time was 240 hours. After the test, the surface corrosion of the two materials was observed using an optical microscope.

[0091] 2. Isothermal oxidation performance test

[0092] The tube furnace was set to operate at 500℃ with a heating rate of 5℃ / min. During the heating process, an Al2O3 crucible was placed in the tube furnace and heated to constant weight to reduce experimental error. Once the furnace temperature reached 500℃, the crucible containing the low surface energy titanium alloy block sample was placed in the homogenization zone of the furnace for oxidation experiments. The holding time was set to 3 hours according to experimental requirements. When the tube furnace temperature reached the preset temperature, the low surface energy titanium alloy block sample was removed periodically and cooled to room temperature. The sample was then measured using a precision of 10... -5 A precision electronic balance is used to weigh the mass change of a sample.

[0093] 3. Salt spray test

[0094] The obtained components were thoroughly cleaned to remove oil stains, and a 6% NaCl solution was prepared, with the pH adjusted to neutral 7.0. The components were then placed in a 35°C chamber and clamped, with the nozzle at a 15° angle to the component surface to ensure that the salt spray freely settled on all exposed surfaces of the part. The test was conducted for 24 hours, after which the morphology was observed using SEM.

[0095] Through the above comparative tests, by placing the additively etched TC4 titanium alloy block sample and the untreated ordinary TC4 titanium alloy block in the same marine corrosion environment, we observed that the surface of the untreated ordinary TC4 titanium alloy block showed tiny, irregular pits and a pale yellow area, indicating slight corrosion. However, the low surface energy titanium alloy block prepared by additive etching according to this invention showed no significant changes. After 24 hours of high-temperature corrosion at 500℃, the mass gain of the component was approximately 0.194 mg / cm³. 2 The added weight is lower than that of titanium alloy components printed by conventional laser printing with wire feeding, indicating that etching and post-processing can slow down the corrosion of the components.

[0096] After 24 hours of salt spray testing, the sample surface was covered with NaCl particles of about 100 μm and surrounded by some small NaCl particles. Apart from this, there was no obvious corrosion on the surface of the component.

[0097] In summary, the metal components prepared by the present invention through laser cladding additive manufacturing and simultaneous composite laser etching process can effectively construct micro-nano protrusion surfaces on printed parts by combining laser additive manufacturing and etching. The combination with ultrasonic fluorination treatment further strengthens the micro-nano protrusion surfaces, thereby endowing the components with excellent self-cleaning ability, significantly enhancing the self-cleaning, corrosion resistance, ice and frost resistance of the metal components, enabling the components to adapt to the deep-sea working environment and improving the service life of the metal components in the deep sea.

[0098] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching, characterized in that, The system includes: Forming base plate; A molding cylinder located below the molding substrate, supporting the molding substrate and capable of driving it to move in a vertical direction; A rotary drive device for driving the molding cylinder and the molding substrate to rotate synchronously in the horizontal direction. Wire feeder, used to transport metal wires for additive manufacturing; A laser cladding head is used to perform laser cladding on a conveyed metal wire using a first process parameter, move along a planned path and deposit components on the surface of the substrate in a layer-by-layer manner; and to perform laser etching on the peripheral outer surface of every n deposited layers using a second process parameter, where n is a positive integer greater than or equal to 1. The laser cladding head is mounted on the spindle of a CNC machining center or the robotic arm of a multi-axis robot, so that it can be driven by the spindle or robotic arm to move along a planned path to perform laser cladding. After being driven to deflect around the deposition layer, it performs laser etching on the peripheral outer surface of the deposition layer to form a surface micro-nano protrusion structure on the peripheral outer surface.

2. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 1, characterized in that, The laser cladding and laser etching processes are performed using the same laser cladding head, and laser processing control is achieved by switching between the first and second process parameters.

3. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing and composite laser etching according to claim 1, characterized in that, The first process parameters used for laser cladding include: The laser power range is 100–400W, the scanning speed is 500–2000 mm / s, the spot diameter is 50–100 μm, the preset printing layer thickness is 20–100 μm, the scanning strategy is checkerboard partition printing, and argon is used as the protective gas.

4. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 1, characterized in that, The second process parameters used for laser etching include: The laser power is 20-300W, the scanning speed is 300-3000mm / s, the pulse frequency is 20-100kHz, the spot diameter is 30-100μm, the defocusing amount is +0.2--0.5mm, the number of scans is 1-6, and the fill spacing spot is 50-90%.

5. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 1, characterized in that, The system is also equipped with an arc-shaped guide rail mounted on the spindle or robotic arm. The laser cladding head is mounted on the arc-shaped guide rail and can be driven to move along the path defined by the arc-shaped guide rail, so that the laser cladding head can deflect around the deposition layer and perform laser etching processing towards the circumferential outer side of the deposition layer.

6. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 5, characterized in that, The arc-shaped guide rail extends from above the molded substrate toward its side, and extends at least on one side to the same height as the initial height of the molded substrate.

7. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 1, characterized in that, The surface micro / nano protrusion structure is a lotus leaf papilla structure.

8. The system for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing and composite laser etching according to claim 1, characterized in that, The laser cladding head is also configured to perform laser etching on the upper surface of the component after the deposition of the entire metal component is completed, forming a surface micro-nano protrusion structure on the upper surface.

9. A method for preparing a low surface energy self-cleaning metal component according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Using metal wire as raw material, the laser cladding additive manufacturing process is adopted. Based on the single-layer deposition thickness of the metal component slice and the planned path, the metal additive deposition is carried out on the molding substrate from the first layer in a bottom-up, layer-by-layer manner until the printing of the entire metal component is completed. In the printing process, starting from the first layer, for each n deposited layer obtained by printing, the laser power, angle, scanning path and the direction of the substrate of the laser cladding head are adjusted to perform laser etching on the peripheral outer surface of each n deposited layer to obtain surface micro-nano protrusion structures, where n is a positive integer greater than or equal to 1. Step S2: Laser etching is performed on the upper surface of the metal component to form a surface micro-nano protrusion structure on the upper surface; Step S3: Heat-treat the metal component with surface micro / nano protrusions. Step S4: Modify the heat-treated metal component with an ultrasonically fluorinated low surface energy material. The fluorinated groups are attached to the surface of the micro-nano protrusion structure by ultrasonic assistance, so that the water contact angle of the component surface exceeds 160°.

10. The method for rapid fabrication of low surface energy self-cleaning metal components using laser additive manufacturing combined with laser etching according to claim 1, characterized in that, The metal wire is selected from one of titanium alloy, steel or aluminum alloy.

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