A laser oxidation marking method of a metal surface weather-resistant two-dimensional code

Abstract

The application discloses a laser oxidation marking method for a metal surface weather-resistant two-dimensional code, relates to the technical field of two-dimensional code marking, and comprises the following steps: composite micro-nano structure-quantum dot synergistic pretreatment, polarization state-three-wavelength time sequence synergistic laser oxidation marking, oxidation atmosphere-micro area electrochemistry synergistic oxidation enhancement, Raman-vision dual-mode online monitoring and double closed loop self-adaptive feedback regulation, gradient annealing-in-situ CVD-dual-response self-repairing triple post-treatment, five-fold protection structure construction, whole-process closed loop quality control and invisible tracing, and whole-process integrated machining, wherein the core processes are continuously completed under the same laser machining station, the same laser head and the same numerical control program control. The method solves the problem that a single process in the prior art cannot simultaneously meet multiple requirements, such as metal adaptation, extreme weather resistance, high precision, high efficiency, self-healing and traceability, and realizes whole-chain innovation from material pretreatment to final protection and from crystal structure control to whole life cycle tracing.

Description

Technical Field

[0001] This invention relates to the field of QR code marking technology, specifically a laser oxidation marking method for weather-resistant QR codes on metal surfaces. Background Technology

[0002] With the rapid development of intelligent manufacturing, the Industrial Internet of Things, and the product lifecycle traceability industry, metal surface QR codes, as the core carrier of product digital identity, are increasingly widely used. In fields such as outdoor facilities, marine engineering, automotive parts, aerospace, and polar engineering, QR codes need to withstand the coupled effects of multiple extreme environmental stresses such as salt spray corrosion, high and low temperature cycling, ultraviolet radiation, mechanical wear, extreme temperature shock, and contaminant adhesion over long periods of time. Therefore, extremely stringent requirements are placed on their weather resistance, marking accuracy, oxide layer adhesion, marking efficiency, and traceability.

[0003] Laser oxidation marking technology has become the mainstream technology for QR code marking on metal surfaces due to its advantages such as being non-contact, permanent, consumable-free, and environmentally friendly. Existing technologies mainly focus on optimizing single laser parameters, generating an oxide layer with color contrast on the metal surface by adjusting parameters such as laser power, frequency, and speed, thereby achieving QR code marking. Some improved solutions employ techniques such as dual-wavelength laser composite marking, laser sintering coating, polarization state control, or simple self-healing coatings, which have improved the marking effect to some extent, but a systematic and synergistic optimization solution has not yet been formed.

[0004] Existing laser oxidation marking methods for QR codes on metal surfaces have the following drawbacks: the oxide film structure is uncontrollable; traditional laser oxidation forms an amorphous or polycrystalline mixed structure with low density, poor corrosion resistance, and weak adhesion between the oxide film and the substrate (≤3N / mm). 2 Post-treatment coatings are mostly physically applied, making them prone to peeling and lacking active protection mechanisms; once damaged, they cannot be repaired. Self-healing capabilities are limited; existing self-healing processes can only repair micro-cracks and cannot withstand extreme temperature shocks below -50℃ or above 800℃. Furthermore, they lack anti-fouling design, and contaminant adhesion can easily affect QR code recognition. Therefore, it is necessary to develop a laser oxidation marking method that overcomes these limitations, achieving multi-metal compatibility, extreme weather resistance, high precision, high efficiency, low cost, and self-healing capabilities. Summary of the Invention

[0005] The purpose of this invention is to provide a laser oxidation marking method for weather-resistant QR codes on metal surfaces, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for laser oxidation marking of weather-resistant QR codes on metal surfaces, comprising the following steps:

[0008] Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots

[0009] A light trap structure, a laser-induced periodic surface structure, a quantum dot-induced seed layer, and a heterogeneous nucleation layer are sequentially formed on the metal surface.

[0010] Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking

[0011] A polarization-tunable three-wavelength laser system is used to perform differentiated marking in different spatial regions of a QR code graphic through a polarization-energy field spatiotemporal coordinated control strategy, and the synergistic effect of the three-wavelength laser is achieved by using a pulse timing misalignment triggering mode.

[0012] Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere

[0013] Multi-physics spatiotemporal synergistic oxidation of laser thermal field, oxidation atmosphere and electrochemical field is achieved by controlling oxidation atmosphere and micro-area electrochemical assistance;

[0014] Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control

[0015] By acquiring Raman spectral signals and CCD visual signals in real time, dual closed-loop adaptive control is performed on the crystal orientation factor and the appearance quality of the QR code.

[0016] Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing

[0017] Gradient temperature field laser annealing, in-situ chemical vapor deposition covalent bonding functionalization, and temperature-sensitive-salt-sensitive dual-response self-healing microcapsule sealing were continuously completed at the same workstation.

[0018] Step S6: Construction of the Five-Layer Protection Structure

[0019] The process involves sequentially performing composite passivation treatment, nano-protective coating spraying and curing, and hydrophobic and antifouling layer spraying and curing to form a five-layer protective structure.

[0020] Step S7: Closed-loop quality control and hidden traceability throughout the entire process

[0021] Quality control is achieved through multi-dimensional detection and environmental simulation testing, and traceability QR codes are invisibly engraved on the edges of the QR codes.

[0022] Step S8: Integrated processing of the entire process, with the core processes being completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The eight-step collaborative technology loop, which integrates composite micro / nano structure-quantum dot synergistic pretreatment, polarization state-three-wavelength time-series synergistic marking, oxidation atmosphere-micro-area electrochemical synergistic enhancement, Raman-visual dual-mode online monitoring and dual closed-loop feedback, triple post-processing, five-fold protection, stealth traceability, and full-process integration, solves the problem that existing technologies cannot simultaneously meet multiple requirements such as multi-metal compatibility, extreme weather resistance, high precision, high efficiency, self-healing, and traceability with a single process; and achieves full-chain innovation from material pretreatment to final protection, and from crystal structure control to full life-cycle traceability.

[0025] 2. Specific parameters for the micro / nano trench optical trap structure, laser-induced periodic surface structure, quantum dot seed layer, and heterogeneous nucleation layer were defined, along with the titanium dioxide coating treatment of the high-reflectivity metal. A four-fold synergistic pretreatment was performed on the femtosecond laser-prefabricated micro / nano trenches, laser-induced periodic surface structure, quantum dot seed layer, and heterogeneous nucleation layer, forming a complete interface control system from physical optical trapping to chemical lattice activation. The micro / nano trench optical trap structure increased the laser absorption rate of the high-reflectivity metal to over 55%; the quantum dot seed layer reduced the activation energy of the oxidation reaction by 30-50%; and the heterogeneous nucleation layer formed a metal-oxide solid solution with a bonding force of no less than 8 N / mm². 2 Titanium dioxide coating increases the absorption rate of high-reflectivity metals by more than 55%, which is 22% higher than existing technologies.

[0026] 3. The polarization state strategy (edge ​​linear polarization, internal circular polarization, and transition elliptical polarization) and pulse timing misalignment triggering mode for functional partition marking are defined. By combining polarization state modulation with the functional partitioning requirements of QR codes, spatial differential control of the crystal structure is achieved. Pulse timing misalignment triggering avoids interference from laser energy superposition. The edge region is dominated by the α phase, providing a high-contrast profile. The internal region is dominated by the γ phase, providing a highly active surface. The transition region has gradient crystal orientation to eliminate abrupt performance changes.

[0027] 4. Specific parameters for dynamic control of the oxidation atmosphere and micro-area electrochemical assistance, as well as the synchronous triggering sequence of laser-electrochemical reaction, were defined. The oxidation atmosphere control, micro-area electrochemical assistance, and laser marking were spatiotemporally coordinated across three physical fields. The design of the laser pulse leading the electrochemical pulse by 5-20 μs ensured precise temporal matching between the thermal and electric fields. The spatiotemporal coordination of the laser thermal and electrochemical fields improved oxidation efficiency by 40%, increased film density by 50%, and reduced the heat-affected zone by 30%. Sodium molybdate formed a molybdate passivation film in situ, enhancing corrosion resistance. Benzotriazole formed a protective film on the copper surface.

[0028] 5. The system defines Raman spectral signal acquisition and crystal orientation factor calculation, CCD visual signal acquisition and appearance quality analysis, and a dual closed-loop adaptive feedback control mechanism. It combines online Raman spectral monitoring with online CCD visual monitoring to achieve dual real-time feedback on crystal structure and appearance quality. The dual closed-loop control system can simultaneously adjust laser parameters and electrochemical parameters. It monitors the crystal orientation factor F=I(612) / I(225) in real time to achieve closed-loop control of crystal structure. The batch-to-batch quality fluctuation is controlled within ±2%. The adaptive feedback control cycle is ≤50ms, and the parameter adjustment accuracy is high.

[0029] 6. The specific composition and parameters of the three-stage gradient annealing process, in-situ CVD covalent bonding functionalization, and temperature-sensitive / salt-sensitive dual-response self-healing microcapsule coating are defined; gradient annealing, in-situ CVD, and dual-response self-healing are completed continuously in the same station without workpiece movement; the temperature-sensitive / salt-sensitive dual-response mechanism can simultaneously cope with microcracks and extreme temperature shocks; gradient annealing promotes α-phase transformation, induces preferred crystal orientation, and eliminates internal stress; in-situ CVD forms a covalently bonded functional layer (Si-O-Metal bond) with a contact angle ≥110°; the self-healing efficiency is ≥90%, and it can repair cracks with a width ≤50μm; the temperature-sensitive repair factor is activated at temperatures below -50℃ or above 810℃ to cope with extreme temperature shocks.

[0030] 7. The specific materials and parameters of the composite passivation treatment, nano-protective coating, and hydrophobic antifouling layer are defined. The passivation layer, nano-protective layer, self-healing layer, and hydrophobic antifouling layer are designed in a five-layer superposition, with each layer complementing each other and providing synergistic protection. The five-layer protection structure forms a complete protection system. The hydrophobic antifouling layer has a contact angle of ≥120° and has oil-proof, antifouling, and waterproof functions. The transparent nano-protective coating has a light transmittance of ≥95% and does not affect QR code scanning.

[0031] 8. The specific items for environmental simulation testing and the design of the invisible traceability QR code are limited. The invisible traceability QR code is integrated with the main QR code to achieve full lifecycle traceability for each QR code, solving the problem of difficulty in defining responsibility for existing process quality. The invisible traceability QR code is only visible under ultraviolet light and does not interfere with the recognition of the main QR code. It contains complete traceability information such as process parameters, processing time, and test results. Non-conforming workpieces are repaired through ultraviolet laser micro-nano correction and local post-processing, with the number of repairs not exceeding 3.

[0032] The range of compatible metal materials and the gradient crystal structure of the film layer are limited; through the synergistic preprocessing of composite micro-nano structure and quantum dot, one solution can be adapted to multiple metal materials; the gradient crystal structure design enables the QR code performance to achieve the optimal balance; it is compatible with more than 8 kinds of metal materials, and the line change debugging time is reduced by 85%; the film crystal structure forms a gradient structure of α phase bottom layer, α / γ mixed phase middle layer, and γ phase surface layer, taking into account corrosion resistance, optical contrast and interface activity. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the composite micro / nano structure-quantum dot synergistic pretreatment structure of the present invention;

[0034] Figure 2 This is a schematic diagram of polarization state-three wavelength time-sequential coordinated laser oxidation marking in this invention;

[0035] Figure 3 The diagram shows the structure and timing control diagram of the oxidation atmosphere-micro-area electrochemical synergistic oxidation enhancement device in this invention.

[0036] Figure 4 The diagram shows the structure and timing control diagram of the oxidation atmosphere-micro-area electrochemical synergistic oxidation enhancement device in this invention.

[0037] Figure 5 This is a layered schematic diagram of the five-layered protective structure in this invention;

[0038] Figure 6 This is a statistical chart comparing the contrast of QR codes on different metal materials using the method of this invention and existing technologies.

[0039] Figure 7 This is a statistical chart comparing the contrast of QR codes on different metal materials using the method of this invention and existing technologies. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] In this embodiment, an extreme weather-resistant QR code was not fabricated on the 316L stainless steel surface.

[0043] Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots

[0044] Femtosecond laser prefabrication of micro-nano trenches: wavelength 1030 nm, pulse width 500 fs, repetition frequency 300 kHz, power 8W, scanning speed 600 mm / s, trench depth 80 nm, width 150 nm, spacing 600 nm.

[0045] Laser-induced periodic surface structure preparation: with the same femtosecond laser parameters, power 5 W, scanning speed 500 mm / s, a spatial period Λ≈600 nm is formed (satisfying 0.2λ≤Λ≤0.8λ, λ=1064 nm).

[0046] Preparation of carbon quantum dots: Citric acid and urea were hydrothermally reacted at 190℃ for 8 h at a mass ratio of 1:2.5 to obtain carbon quantum dots with a particle size of 5-8 nm.

[0047] Preparation of iron oxide quantum dots: Iron nitrate was thermally decomposed at 280℃ to obtain iron oxide quantum dots with a particle size of 8-12 nm.

[0048] Quantum dot seed layer deposition: Carbon quantum dots, iron oxide quantum dots, and KH550 silane coupling agent are mixed in a mass ratio of 2:3:6, and deposited by spin coating (2000 rpm) to a thickness of 150 nm, and cured at 120℃ for 30 min.

[0049] Laser-induced heteronucleation: 532 nm green laser, power 12W, scanning speed 400 mm / s, induction time 15s, forming a 35 nm thick Fe-Fe2O3 solid solution heteronucleation layer.

[0050] Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking

[0051] Three-wavelength laser system: femtosecond laser (1064 nm, 500 fs, 30 W), green laser (532 nm, 5 ns, 15 W), ultraviolet laser (355 nm, 20 ns, 8 W), coaxial beam combiner.

[0052] Functional partition labeling parameters:

[0053] Module edge region (0.06 mm wide): linearly polarized light (angle 15°), femtosecond laser, energy density 260 J / cm² 2 Frequency 40kHz, velocity 280 mm / s, linear energy density 1.2 J / cm;

[0054] Internal region of the module: Circularly polarized light, femtosecond laser, energy density 130 J / cm² 2 Frequency 150kHz, speed 550mm / s, linear energy density 0.6 J / cm;

[0055] Boundary transition region (width 0.03 mm): Elliptically polarized light (ellipticity 0.5), ultraviolet laser, power 35%, velocity 180 mm / s.

[0056] Pulse timing: Femtosecond laser leads green laser by 15μs, green laser leads ultraviolet laser by 20μs.

[0057] Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere

[0058] Oxidizing atmosphere: Argon / Oxygen ratio 3:1, pressure 0.2MPa, oxygen content 25%.

[0059] Electrolyte: 0.05 mol / L sodium nitrate + 0.01 mol / L sodium molybdate + 0.002 mol / L benzotriazole, pH=7.2, temperature 30℃, spray pressure 0.3MPa, droplet diameter 100μm, spray angle 45°.

[0060] Electrochemical parameters: pulse potential -0.2V to +1.0V vs. Ag / AgCl, frequency 50Hz, duty cycle 50%, laser pulse leads electrochemical pulse by 12μs.

[0061] Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control

[0062] Raman parameters: excitation wavelength 532 nm, resolution 1.5 cm. -1 Integration time 50 ms, sampling frequency 200 Hz.

[0063] CCD parameters: 5 megapixel resolution, 90fps frame rate.

[0064] The crystal orientation factor F has a preset threshold of 2.5±0.5. Real-time monitoring shows that the F value is in the range of 2.3-2.7, and no adjustment is required.

[0065] Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing

[0066] Gradient annealing: Gaussian gradient temperature field (central power density 2.2 J / cm²) 2 0.5 J / cm at the edge 2 ), 250℃ for 45s → 450℃ for 30s → 320℃ for 45s.

[0067] In-situ CVD: hexamethyldisiloxane as the reaction precursor, nitrogen as the carrier gas at 100 sccm, reaction pressure at 0.05 MPa, deposition thickness at 80 nm, and contact angle at 115°.

[0068] Self-healing coating: 20% self-healing microcapsules (core material: methyl linoleate: molybdate corrosion inhibitor = 3:1, particle size 10μm), 5% thermosensitive nano-repair factor (TiO2 nanoparticles), 8% nanofiller (SiO2:CeO2 = 2:1), 67% silicone-modified epoxy resin, spray thickness 6μm, cured at 120℃ for 90 min.

[0069] Step S6: Construction of the Five-Layer Protection Structure

[0070] Passivation treatment: Primary passivation with nitric acid passivation solution (20% nitric acid + 2% potassium dichromate) for 6 min → secondary sealing with silane sealing agent for 2 min.

[0071] Nano protective layer: Fluorocarbon nano varnish spraying, 4μm thick, UV cured for 30 s.

[0072] Hydrophobic and antifouling layer: Nano-fluorocarbon coating sprayed, 1.5μm thick, cured at room temperature for 25 min.

[0073] Step S7: Closed-loop quality control and hidden traceability throughout the entire process

[0074] Test results: QR code grade A (4.0 / 4.0), contrast ratio 0.95, oxide layer thickness 5.5μm, adhesion strength 8.5 N / mm 2 It maintains a readability grade of Grade B or above after 6500 hours of salt spray testing, with a self-healing efficiency of 92%.

[0075] Invisible traceability QR code: engraved with ultraviolet laser, size 0.1 mm × 0.1 mm, containing process parameters, processing time, and test result information.

[0076] (8) Step S8: Integrated processing of the entire process

[0077] The processing time for a single piece is 55 seconds, the batch production efficiency is 550 pieces / hour, and the pass rate is 99.6%.

[0078] Example 2

[0079] like Figures 1-7 As shown: A laser oxidation marking method for weather-resistant QR codes on metal surfaces, comprising the following steps:

[0080] Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots

[0081] A light trap structure, a laser-induced periodic surface structure, a quantum dot-induced seed layer, and a heterogeneous nucleation layer are sequentially formed on the metal surface.

[0082] Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking

[0083] A polarization-tunable three-wavelength laser system is used to perform differentiated marking in different spatial regions of a QR code graphic through a polarization-energy field spatiotemporal coordinated control strategy, and the synergistic effect of the three-wavelength laser is achieved by using a pulse timing misalignment triggering mode.

[0084] Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere

[0085] Multi-physics spatiotemporal synergistic oxidation of laser thermal field, oxidation atmosphere and electrochemical field is achieved by controlling oxidation atmosphere and micro-area electrochemical assistance;

[0086] Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control

[0087] By acquiring Raman spectral signals and CCD visual signals in real time, dual closed-loop adaptive control is performed on the crystal orientation factor and the appearance quality of the QR code.

[0088] Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing

[0089] Gradient temperature field laser annealing, in-situ chemical vapor deposition covalent bonding functionalization, and temperature-sensitive-salt-sensitive dual-response self-healing microcapsule sealing were continuously completed at the same workstation.

[0090] Step S6: Construction of the Five-Layer Protection Structure

[0091] The process involves sequentially performing composite passivation treatment, nano-protective coating spraying and curing, and hydrophobic and antifouling layer spraying and curing to form a five-layer protective structure.

[0092] Step S7: Closed-loop quality control and hidden traceability throughout the entire process

[0093] Quality control is achieved through multi-dimensional detection and environmental simulation testing, and traceability QR codes are invisibly engraved on the edges of the QR codes.

[0094] Step S8: Integrated processing of the entire process, with the core processes being completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program.

[0095] The eight-step collaborative technology loop, which integrates composite micro / nano structure-quantum dot synergistic pretreatment, polarization state-three-wavelength time-series synergistic marking, oxidation atmosphere-micro-area electrochemical synergistic enhancement, Raman-visual dual-mode online monitoring and dual closed-loop feedback, triple post-processing, five-fold protection, stealth traceability, and full-process integration, solves the problem that existing technologies cannot simultaneously meet multiple requirements such as multi-metal compatibility, extreme weather resistance, high precision, high efficiency, self-healing, and traceability with a single process; and achieves full-chain innovation from material pretreatment to final protection, and from crystal structure control to full life-cycle traceability.

[0096] Example 3

[0097] like Figures 1-7 As shown: A laser oxidation marking method for weather-resistant QR codes on metal surfaces, comprising the following steps:

[0098] Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots

[0099] By combining femtosecond laser-prefabricated micro / nano trench optical trap structures, laser-induced periodic surface structures, quantum dot-induced seed layers, and laser-induced interface heterogeneous nucleation in a four-fold synergistic manner, the metal surface is fully activated from both physical and chemical levels, providing ideal lattice templates and nucleation sites for subsequent oxidation.

[0100] (1) Femtosecond laser prefabrication of micro-nano trench optical trap structure

[0101] Nanoscale micro- and nano-grooves (depth 50-200 nm, width 100-200 nm) are pre-fabricated on the surface of a metal substrate using femtosecond lasers. The grooves are distributed in a grid pattern with a spacing of 500-800 nm. The mechanism of action of this structure includes:

[0102] Light trapping effect: The laser is reflected multiple times in the trench, so that the energy is fully absorbed. For highly reflective metals, the laser absorption rate can be increased to more than 55%.

[0103] Stress concentration effect: Stress concentration occurs at the edge of the trench, providing an energy advantage for preferential nucleation of the oxide film;

[0104] Mechanical anchoring effect: The groove structure increases the contact area between the oxide film and the substrate, enhancing adhesion.

[0105] (2) Laser-induced periodic surface structure preparation

[0106] A periodic micro / nano structure with a spatial period Λ satisfying 0.2λ≤Λ≤0.8λ (where λ is the wavelength of the subsequent marking laser) is formed using an ultrashort pulse laser. The structure orientation forms an angle of 30° to 90° with the scanning direction of the subsequent marking laser. The mechanism of this structure includes:

[0107] Optical antenna effect: Through the surface plasmon resonance effect, subsequent laser energy is efficiently coupled to the metal surface;

[0108] Energy periodic modulation: This causes the oxidation reaction to be distributed periodically in space, forming a uniform oxide film.

[0109] (3) Quantum dot-induced seed layer deposition

[0110] Seed layers composed of carbon quantum dots, metal oxide quantum dots, and silane coupling agents are deposited on the surface of periodic micro / nano structures:

[0111] Carbon quantum dots: They possess excellent photocatalytic properties, generating electron-hole pairs under laser irradiation, promoting the activation of oxygen molecules into reactive oxygen species, and reducing the activation energy of oxidation reactions by 30-50%;

[0112] Metal oxide quantum dots: as preferential nucleation sites for oxidation reactions, their lattice constant matches that of the oxide in the metal matrix, inducing subsequent epitaxial growth of oxide films;

[0113] Silane coupling agent: forms MO-Si chemical bonds, establishes chemical bridging between quantum dots and the metal matrix, and enhances adhesion.

[0114] (4) Laser-induced interfacial heterogeneous nucleation

[0115] A 532nm green laser was used to induce interfacial heterogeneous nucleation, forming a 20-50 nm metal-oxide solid solution heterogeneous nucleation layer. The functions of this layer include:

[0116] Lattice matching: The lattice constant of the heterogeneous nucleation layer is between that of the substrate and the oxide film, which reduces the interfacial energy;

[0117] Compositional transition: Forms a compositional gradient from the base metal to the oxide, eliminating interfacial stress;

[0118] Enhanced activity: The heterogeneous nucleation layer has a high density of lattice defects, providing abundant active sites for oxidation reactions.

[0119] Special treatment for highly reflective metals: For highly reflective metals such as copper, gold, and silver, an additional 5-8 nm titanium dioxide thin film is vacuum-deposited before the quantum dot-induced seed layer deposition. The TiO2 thin film has both an anti-reflection effect (reducing surface reflectivity) and a lattice matching effect (the lattice mismatch between TiO2 and the oxides of metals such as copper and silver is less than 5%), increasing the laser absorption rate to over 55%.

[0120] Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking

[0121] First, a polarization state-energy field spatiotemporal coordinated control strategy is adopted to perform functional partitioning in different spatial regions of the QR code graphic; second, three-wavelength laser coaxial beam combining and pulse timing misalignment triggering are used to achieve the synergistic effect of femtosecond laser (forming the oxide film bottom layer), green laser (precise oxygen replenishment for highly reflective metals), and ultraviolet laser (micro-nano-level fine correction).

[0122] (1) Spatiotemporal coordinated regulation of polarization state and energy field

[0123] Based on the fundamental requirements of QR code recognition, the QR code image is divided into three functional areas:

[0124] area polarization state laser source Energy density Effects Module edge area Linearly polarized light Femtosecond laser <![CDATA[E 1 ≥ 2E th ]]> Carbon migration is dominant, α phase is predominant, deep black with high contrast, and a thickness of 5-8 μm. Internal area of ​​the module Circularly polarized light Femtosecond laser <![CDATA[0.6E th ≤E2≤1.2E th ]]> Oxidation-dominated, γ-phase-predominant, highly active surface, 2-4 μm thick Boundary transition area Elliptically polarized light Ultraviolet laser Continuous gradient Gradient crystal orientation eliminates abrupt performance changes; thickness 4-6 μm

[0125] (2) Coaxial beam combining of three-wavelength lasers and triggering of pulse timing misalignment

[0126] Three-wavelength lasers are coaxially combined using a dichroic mirror, with an energy distribution ratio of (40-60)%:(20-30)%:(15-25)%. A pulse timing misalignment triggering mode is employed.

[0127] The femtosecond laser pulse leads the green laser pulse by 10-20 μs;

[0128] The green laser pulse precedes the ultraviolet laser pulse by 15-25μs.

[0129] The mechanism of this timing design is as follows: the femtosecond laser first forms the initial oxide layer, the green laser supplements the oxide layer on the basis of the initial oxide layer (especially for highly reflective metals), and the ultraviolet laser performs micro-nano-level shaping to avoid interference from laser energy superposition, thereby achieving precise energy allocation and timing coordination.

[0130] (3) Mechanism of functional zoning and crystal orientation control

[0131] Linearly polarized light induces the formation of α-Fe₂O₃ (hematite) crystals, which have a hexagonal close-packed structure, high chemical stability, and excellent corrosion resistance. Circularly polarized light induces the formation of γ-Fe₂O₃ (magnesite) crystals, which have a cubic spinel structure and high optical contrast. Elliptically polarized light forms a gradient crystal orientation transition structure. Through this design, the edge region of the QR code obtains a high-contrast contour (ensuring the geometric positioning of the scanning device), the internal region obtains a highly active surface (providing active sites for subsequent bonding), and the transition region eliminates abrupt performance changes.

[0132] Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere

[0133] By synergistically combining the regulation of the oxidation atmosphere with micro-area electrochemical assistance, a multi-physics field coupled oxidation of laser thermal field, oxidation atmosphere and electrochemical field is formed.

[0134] (1) Dynamic control of oxidation atmosphere

[0135] The local oxidation atmosphere is controlled by dynamically adjusting the ratio of inert gas (argon or nitrogen) to oxygen (1:1 to 5:1), with the pressure maintained between 0.1 and 0.3 MPa. The oxygen ratio is dynamically adjusted based on the metal material.

[0136] High reflectivity metals: Oxygen content 30%-40% (promotes oxidation reaction);

[0137] Stainless steel and aluminum alloys: oxygen content 20%-30%;

[0138] Titanium alloys: oxygen content 15%-25% (to avoid excessive oxidation).

[0139] (2) Micro-area electrochemical assistance

[0140] The micro-area electrolyte spraying system synchronously sprays an electrolyte containing sodium nitrate (supporting electrolyte), sodium molybdate (corrosion inhibitor precursor), and benzotriazole (copper corrosion inhibitor) into the laser-affected area. A pulsed potential (-0.3V to +1.2V; Ag / AgCl, pulse frequency 10-100Hz, duty cycle 30-70%) is applied.

[0141] (3) Spatiotemporal synergy of laser-electrochemical-oxidation atmosphere

[0142] The laser pulse and the electrochemical pulse are triggered synchronously, with the laser pulse leading the electrochemical pulse by 5-20 μs. The mechanism of this timing design is as follows:

[0143] The laser pulse first acts on the metal surface, generating localized high temperatures and activating the metal surface;

[0144] An electrochemical pulse is applied at the peak of the thermal field after laser irradiation to enhance the electrochemical reaction kinetics using the thermal field.

[0145] The oxidation atmosphere control module provides sufficient reactive oxygen species;

[0146] Sodium molybdate decomposes under electrochemical action, forming a molybdate passivation film (MoO4) in the oxide film. 2- It forms insoluble molybdates with metal ions, significantly enhancing corrosion resistance;

[0147] Benzotriazole forms a protective film on the copper surface, inhibiting copper corrosion.

[0148] The advantages of this multi-physics synergistic oxidation include: 40% increase in oxidation efficiency, 50% increase in film density, and 30% reduction in the heat-affected zone.

[0149] Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control

[0150] Simultaneously acquiring Raman spectral signals (for crystal structure analysis) and CCD visual signals (for QR code appearance analysis), the system achieves dual real-time monitoring of crystal structure and appearance quality, and enables adaptive adjustment of process parameters through a dual closed-loop intelligent control system.

[0151] (1) Online monitoring of Raman spectroscopy

[0152] The Raman spectroscopy acquisition module acquires characteristic peaks of the oxide film in real time:

[0153] α-Fe₂O₃ characteristic peak: 225 cm⁻¹ -1 293 cm -1 410 cm -1 612 cm -1 ;

[0154] Characteristic peak of γ-Fe2O3: 350 cm⁻¹ -1 500 cm -1 700 cm -1 .

[0155] Calculate the crystal orientation factor F = I(612 cm). -1 ) / I(225 cm -1 The F value is positively correlated with the corrosion resistance of the oxide film. The higher the F value, the higher the α phase content and the better the corrosion resistance; however, when the F value is too high, the γ phase content is too low, and the optical contrast decreases. Therefore, the preset threshold of F is set to 1.5-3.5 according to the metal material and application scenario to achieve a balance between corrosion resistance and contrast.

[0156] (2) CCD visual online monitoring

[0157] The CCD vision system acquires real-time images of the QR code's appearance and analyzes its contrast, edge roughness, module integrity, and ISO / IEC 15415 rating. Feedback adjustments are triggered when the contrast falls below 85% or the QR code rating is below Grade A.

[0158] (3) Dual closed-loop adaptive feedback control

[0159] The dual-loop intelligent control system is equipped with a deep learning algorithm and pre-stores oxidation parameters and crystal structure models of various metals. When the crystal orientation factor F deviates from the preset threshold by ±20%, the contrast is below 85%, or the QR code level is below Grade A, the system automatically adjusts.

[0160] The laser polarization state, power, and scanning speed in step S2;

[0161] The electrochemical potential and oxidizing atmosphere ratio in step S3.

[0162] The adaptive feedback control cycle is ≤50ms, and the parameter adjustment accuracy is: laser power ±1%, scanning speed ±2%, potential ±0.05V, and oxidation atmosphere ratio ±2%.

[0163] Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing

[0164] The triple post-processing of gradient annealing texturing, in-situ chemical vapor deposition covalent bonding functionalization, and temperature- and salt-sensitive dual-response self-healing microcapsule sealing can be completed continuously at the same workstation without moving the workpiece.

[0165] (1) Gradient temperature field laser annealing texturing

[0166] The annealing laser beam is intensity modulated using a spatial light modulator to achieve a central power density of 1-3 J / cm². 2Edge power density: 0.3-0.8 J / cm³ 2 A Gaussian gradient temperature field with a gradient of 5-15 ℃ / mm. Three-stage annealing process:

[0167] First stage (200-300℃, 30-60s): Promotes the transformation of amorphous phase to α phase;

[0168] Second stage (400-500℃, 20-40s): Inducing preferential orientation growth of crystals;

[0169] The third stage (300-350℃, 30-60s): Eliminating internal stress.

[0170] (2) In-situ chemical vapor deposition covalent bonding functionalization

[0171] While maintaining the relative position of the laser head and the workpiece, a reactive precursor containing fluorine, silicon, or phosphorus (such as fluorosilanes, phosphosilicates, or organometallic siloxanes) is introduced through a coaxial nozzle. The residual thermal field (temperature of approximately 80-150℃ in the QR code area) induces selective chemical vapor deposition of the reactive precursor on the QR code surface, forming a hydrophobic and oleophobic self-assembled monolayer with a thickness of 20-200 nm. This layer is bonded to the underlying chemically modified layer via Si-O-Metal or PO-Metal covalent bonds, with a contact angle ≥110° and a roll-off angle ≤10°.

[0172] (3) Thermosensitive-saltsensitive dual-response self-healing microcapsule sealing

[0173] The self-healing composite coating consists of the following components:

[0174] Self-healing microcapsules (15-25%): The core material is methyl linoleate and molybdate corrosion inhibitor (mass ratio 2-4:1), and the wall material is urea-formaldehyde resin or polyurea, with a particle size of 5-20 μm. Crack triggering conditions: crack width ≥1 μm, or local pH change ≥2 units, or chloride ion concentration ≥0.01 mol / L;

[0175] Thermosensitive nano-repair factor (3-8%): Activation temperature is below -50℃ or above 810℃, which can cope with extreme temperature shocks;

[0176] Nanofillers (5-10%): Nano silica and nano cerium oxide, to enhance the density and wear resistance of the coating;

[0177] Film-forming resin (65-80%): Organosilicon-modified epoxy resin or fluorocarbon resin.

[0178] After the coating is sprayed, it is cured at 100-150℃ for 60-120 min, and the self-healing efficiency is ≥90%.

[0179] Step S6: Construction of the Five-Layer Protection Structure

[0180] Based on the self-healing microcapsule sealing, the following processes are performed sequentially to form a five-layer protective structure:

[0181] Protective layer Materials / Process thickness effect Dense oxide marking layer Laser oxidation formation 3-10μm Basic protection, providing contrast passivation transition layer Material-compatible composite passivation Less than 1μm Chemical passivation enhances corrosion resistance Nano protective layer Fluorocarbon nano varnish 3-5μm Physical protection, UV blocking Dual-response self-healing layer Self-healing microcapsule coating 3-8μm Self-healing cracks, protection against extreme temperatures Hydrophobic and antifouling layer Nano-fluorocarbon coating 1-2μm Self-cleaning, oil-proof, stain-proof and waterproof

[0182] Among them, the material-adaptive composite passivation treatment adopts a composite method of "main passivation and auxiliary sealing", and selects an appropriate passivation system for different metal materials; the transparent nano-protective coating is cured by ultraviolet light and has a light transmittance of ≥95%; the hydrophobic and antifouling layer has a contact angle of ≥120°.

[0183] Step S7: Closed-loop quality control and hidden traceability throughout the entire process

[0184] (1) Full-process quality inspection

[0185] The QR codes are comprehensively inspected using a laser confocal microscope (to detect oxide layer thickness with an accuracy of ±0.1μm), an industrial barcode scanner (reading speed ≥100 times / second), and environmental simulation tests (salt spray test ≥6000h, UV aging ≥10000h, high temperature test 850℃, friction test 1500 cycles, and high and low temperature cycle -55℃~850℃ 150 cycles). Defective workpieces are repaired using UV laser micro-nano correction and local post-processing, with a maximum of three repair attempts.

[0186] (2) Invisible traceability QR code

[0187] A traceability QR code, invisiblely engraved with process parameters, is used on the edge of the main QR code. This engraving, employing ultraviolet laser engraving, is 1 / 5 the size of the main QR code and is only visible under ultraviolet light. This traceability QR code contains the following information:

[0188] Process parameters: laser power, scanning speed, polarization state, electrochemical potential, oxidation atmosphere ratio, etc.

[0189] Processing time: timestamp accurate to the second;

[0190] Test results: QR code grade, contrast, oxide layer thickness, etc.

[0191] Equipment information: Equipment number, operator, etc.

[0192] This design enables full lifecycle traceability of each QR code, solving the problem of difficulty in defining responsibility for quality in existing processes.

[0193] Step S8: Integrated processing of the entire process

[0194] The core processes from steps S1 to S7 are completed continuously at the same laser processing station, with the same laser head and the same CNC program control, without the need to move the workpiece or change equipment. The advantages of this design include:

[0195] Highly integrated processes: single-piece processing time ≤ 60s, shortening the time by more than 60% compared to the traditional "marking and post-processing" method;

[0196] High positioning accuracy: No need for repeated positioning, avoiding cumulative errors;

[0197] High degree of automation: easy to integrate into automated production lines;

[0198] Cost controllable: The investment cost is only 55% of that of configuring multiple devices individually.

[0199] Example 4

[0200] like Figures 1-7 As shown: A laser oxidation marking method for weather-resistant QR codes on metal surfaces, comprising the following steps:

[0201] Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots

[0202] The following processes are performed sequentially on the metal surface to be marked:

[0203] (a) Femtosecond laser prefabrication of micro-nano trench optical trap structure: A femtosecond laser is used to perform a first scan on the surface of a metal substrate to form nano-scale micro-nano trenches with a depth of 50-200 nm and a width of 100-200 nm. The micro-nano trenches are distributed in a grid pattern with a trench spacing of 500-800 nm to form an optical trap structure.

[0204] (b) Laser-induced periodic surface structure preparation: A second scan is performed on the surface of a metal substrate using an ultrashort pulse laser to form a laser-induced periodic surface structure with a spatial period Λ satisfying 0.2λ≤Λ≤0.8λ, where λ is the wavelength of the subsequent marking laser. The orientation of the periodic micro / nano structure is at an angle of 30° to 90° with the scanning direction of the subsequent marking laser.

[0205] (c) Quantum dot-induced seed layer deposition: A quantum dot-induced seed layer composed of carbon quantum dots, metal oxide quantum dots and silane coupling agent in a mass ratio of 1-3:2-4:5-8 is deposited on the surface of a periodic micro / nano structure. The carbon quantum dots have a particle size of 3-10 nm, the metal oxide quantum dots have a particle size of 5-15 nm, and the seed layer has a thickness of 50-300 nm.

[0206] (d) Laser-induced interface heterogeneous nucleation: Green laser is used to induce interface heterogeneous nucleation to form a metal-oxide solid solution heterogeneous nucleation layer with a thickness of 20-50 nm;

[0207] For high-reflectivity metals, an additional 5-8 nm titanium dioxide thin film is deposited under vacuum before the quantum dot-induced seed layer deposition.

[0208] The specific parameters of the micro / nano trench optical trap structure, laser-induced periodic surface structure, quantum dot seed layer, and heterogeneous nucleation layer were defined, along with the titanium dioxide coating treatment of the high-reflectivity metal. A four-fold synergistic pretreatment of the femtosecond laser-prefabricated micro / nano trenches, laser-induced periodic surface structure, quantum dot seed layer, and heterogeneous nucleation layer was performed to form a complete interface control system from physical optical trapping to chemical lattice activation. The micro / nano trench optical trap structure increased the laser absorption rate of the high-reflectivity metal to over 55%; the quantum dot seed layer reduced the activation energy of the oxidation reaction by 30-50%; and the heterogeneous nucleation layer formed a metal-oxide solid solution with a bonding force of no less than 8 N / mm². 2 Titanium dioxide coating increases the absorption rate of high-reflectivity metals by more than 55%, which is 22% higher than existing technologies.

[0209] Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking

[0210] A polarization-tunable three-wavelength laser system is used to scan a QR code pattern on a metal surface. The polarization-tunable three-wavelength laser system includes a femtosecond laser source, a green laser source, an ultraviolet laser source, and a polarization modulation module. The three wavelength lasers are combined coaxially through a dichroic mirror.

[0211] The laser scanning employs a polarization state-energy field spatiotemporal coordinated control strategy, using differentiated combinations of polarization states and laser parameters in different spatial regions of the QR code graphic, and adopting a pulse timing misalignment triggering mode.

[0212] (a) In the edge region of the QR code graphic module, linearly polarized light combined with femtosecond laser is used for scanning, with the polarization direction and scanning direction at an angle of 0°-30°, and the laser energy density E1 not less than 2E th The pulse frequency f1 is not higher than 0.5f opt The linear energy density is 0.8-1.5 J / cm, the scanning speed is 200-400 mm / s, and it induces a deep chemical transformation in metal dominated by carbon migration, forming a high-contrast edge profile with a thickness of 5-8 μm, mainly composed of α phase crystals.

[0213] (b) Within the module area of ​​the QR code graphic, circularly polarized light combined with a femtosecond laser is used for scanning, with a laser energy density of 0.6E. th ≤ E2≤ 1.2E th The pulse frequency f2 ≥ 1.2f optThe linear energy density is 0.3-0.8 J / cm, the scanning speed is 500-800 mm / s, and it induces a shallow chemical transformation of the metal dominated by oxidation, forming an internal filling with a thickness of 2-4 μm, mainly composed of γ phase crystals.

[0214] (c) In the module boundary transition area of ​​the QR code graphic, elliptic polarized light is used in combination with ultraviolet laser for scanning. The ellipticity is 0.3-0.7, and the laser energy density and pulse frequency are continuously and gradually changed between E1 and E2 and between f1 and f2 to form a gradient crystal orientation transition layer with a thickness of 4-6μm.

[0215] (d) For highly reflective metals, an additional green laser is activated for precise oxygen supplementation marking, with a power of 50%-60% of the maximum power and a speed of 300-400 mm / s;

[0216] The pulse timing misalignment triggering mode is as follows: the femtosecond laser pulse leads the green laser pulse by 10-20 μs, and the green laser pulse leads the ultraviolet laser pulse by 15-25 μs, to avoid laser energy superposition interference.

[0217] Among them, E th f is the critical energy density for carbon migration in a metallic matrix. opt Optimized frequency to achieve the highest oxidation efficiency;

[0218] The polarization state strategy (edge ​​linear polarization, internal circular polarization, and transition elliptical polarization) and pulse timing misalignment triggering mode for functional partition marking are defined. By combining polarization state modulation with the functional partitioning requirements of QR codes, spatial differential control of the crystal structure is achieved. Pulse timing misalignment triggering avoids interference from laser energy superposition. The edge region is dominated by the α phase, providing a high-contrast profile. The internal region is dominated by the γ phase, providing a highly active surface. The transition region has gradient crystal orientation to eliminate abrupt performance changes.

[0219] Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere

[0220] An oxidation atmosphere control module and a micro-area electrochemical auxiliary device are set up in the laser-acting region to achieve synergistic oxidation using multiple physical fields:

[0221] (a) The oxidation atmosphere control module controls the local oxidation atmosphere by dynamically adjusting the ratio of inert gas to oxygen, with the ratio ranging from 1:1 to 5:1 and the pressure controlled at 0.1-0.3 MPa;

[0222] (b) The micro-area electrochemical auxiliary device synchronously sprays an electrolyte containing 0.01-0.1 mol / L sodium nitrate, 0.005-0.02 mol / L sodium molybdate and 0.001-0.005 mol / L benzotriazole into the laser-acting area and applies a pulsed potential;

[0223] The laser pulse and the electrochemical pulse are triggered synchronously, with the laser pulse leading the electrochemical pulse by 5-20 μs, forming a spatiotemporal synergistic oxidation of the laser thermal field, the oxidation atmosphere, and the electrochemical field;

[0224] The specific parameters for dynamic control of the oxidation atmosphere and micro-area electrochemical assistance, as well as the synchronous triggering sequence of laser-electrochemical reaction, were defined. The oxidation atmosphere control, micro-area electrochemical assistance, and laser marking were spatiotemporally coordinated using three physical fields. The design of the laser pulse leading the electrochemical pulse by 5-20 μs ensured precise temporal matching between the thermal and electric fields. The spatiotemporal coordination of the laser thermal and electrochemical fields improved oxidation efficiency by 40%, increased film density by 50%, and reduced the heat-affected zone by 30%. Sodium molybdate formed a molybdate passivation film in situ, enhancing corrosion resistance. Benzotriazole formed a protective film on the copper surface.

[0225] Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control

[0226] During the laser action, data is collected in real time via a dual-mode monitoring module:

[0227] (a) Raman spectral signal: excitation wavelength 532 nm or 633 nm, spectral resolution 1-2 cm⁻¹ -1 Integration time 10-100 ms, acquisition frequency 100-500 Hz, analysis of α-Fe2O3 characteristic peak (225 cm⁻¹) -1 293 cm -1 410 cm -1 612 cm -1 and γ-Fe2O3 characteristic peak (350 cm⁻¹) -1 500 cm -1 700 cm -1 ), calculate the crystal orientation factor F = I(612 cm), -1 ) / I(225cm -1 );

[0228] (b) CCD visual signal: resolution of 5 million pixels or more, frame rate of 60-120fps, to acquire QR code appearance images and analyze contrast, edge roughness, module integrity and ISO / IEC 15415 level;

[0229] When the crystal orientation factor F deviates from the preset threshold by ±20%, or the contrast is lower than 85%, or the QR code level is lower than Grade A, the dual closed-loop intelligent control system automatically adjusts the laser polarization state, power, and scanning speed in step S2 and the electrochemical potential and oxidation atmosphere ratio in step S3, with an adaptive feedback control cycle of no more than 50 ms.

[0230] The system defines Raman spectral signal acquisition and crystal orientation factor calculation, CCD visual signal acquisition and appearance quality analysis, and a dual-closed-loop adaptive feedback control mechanism. It combines online Raman spectral monitoring with online CCD visual monitoring to achieve dual real-time feedback on crystal structure and appearance quality. The dual-closed-loop control system can simultaneously adjust laser parameters and electrochemical parameters. Real-time monitoring of the crystal orientation factor F=I(612) / I(225) enables closed-loop control of the crystal structure. Batch-to-batch quality fluctuations are controlled within ±2%. The adaptive feedback control cycle is ≤50ms, and parameter adjustment accuracy is high.

[0231] Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing

[0232] The following three post-processing steps can be completed consecutively at the same workstation without moving the workpiece:

[0233] (a) Gradient temperature field laser annealing texturing: The intensity of the annealing laser beam is modulated using a spatial light modulator to achieve a central power density of 1-3 J / cm². 2 Edge power density: 0.3-0.8 J / cm³ 2 The temperature field has a Gaussian gradient, with a gradient of 5-15 ℃ / mm, and annealing is performed in the following stages:

[0234] First stage: Temperature 200-300℃, hold for 30-60s to promote the transformation of amorphous phase to α phase;

[0235] Second stage: Temperature 400-500℃, hold for 20-40s to induce preferential orientation growth of crystals;

[0236] Third stage: Temperature 300-350℃, heat preservation for 30-60s, to eliminate internal stress;

[0237] (b) In-situ chemical vapor deposition covalent bonding functionalization: Keeping the relative position of the laser head and the workpiece unchanged, a reactive precursor containing fluorine, silicon or phosphorus elements of organometallic compound is introduced through a coaxial nozzle. The residual thermal field induces selective chemical vapor deposition on the QR code surface to form a hydrophobic and oleophobic self-assembled monolayer with a thickness of 20-200 nm. It is bonded to the underlying chemically modified layer through Si-O-Metal or PO-Metal covalent bonds, with a contact angle of not less than 110°.

[0238] (c) Thermosensitive-saltsensitive dual-response self-healing microcapsule sealing: A self-healing composite coating is sprayed onto the surface of the covalently bonded functional layer. The coating consists of self-healing microcapsules, thermosensitive nano-repair factors, nanofillers and film-forming resin, and the coating thickness is 3-8 μm.

[0239] The specific composition and parameters of the three-stage gradient annealing process, in-situ CVD covalent bonding functionalization, and temperature-sensitive / salt-sensitive dual-response self-healing microcapsule coating were defined. Gradient annealing, in-situ CVD, and dual-response self-healing were completed continuously in the same station without workpiece movement. The temperature-sensitive / salt-sensitive dual-response mechanism can simultaneously cope with microcracks and extreme temperature shocks. Gradient annealing promotes α-phase transformation, induces preferred crystal orientation, and eliminates internal stress. In-situ CVD forms a covalently bonded functional layer (Si-O-Metal bond) with a contact angle ≥110°. The self-healing efficiency is ≥90%, and it can repair cracks with a width ≤50μm. The temperature-sensitive repair factor is activated at temperatures below -50℃ or above 810℃ to cope with extreme temperature shocks.

[0240] Step S6: Construction of the Five-Layer Protection Structure

[0241] Based on the self-healing microcapsule sealing, material-adaptive composite passivation treatment, transparent nano-protective coating spraying and curing, and hydrophobic antifouling layer spraying and curing are carried out in sequence to form a five-fold protective structure consisting of a dense oxide marking layer, a passivation transition layer, a nano-protective layer, a temperature-sensitive and salt-sensitive dual-response self-healing layer, and a hydrophobic antifouling layer.

[0242] The specific materials and parameters of the composite passivation treatment, nano-protective coating, and hydrophobic antifouling layer are defined. The passivation layer, nano-protective layer, self-healing layer, and hydrophobic antifouling layer are designed in a five-layer superposition, with each layer complementing each other and providing synergistic protection. The five-layer protection structure forms a complete protection system. The hydrophobic antifouling layer has a contact angle of ≥120° and has oil-proof, antifouling, and waterproof functions. The transparent nano-protective coating has a light transmittance of ≥95% and does not affect QR code scanning.

[0243] Step S7: Closed-loop quality control and hidden traceability throughout the entire process

[0244] (a) The thickness, recognition rate and weather resistance of the QR code oxide layer are comprehensively tested by laser confocal microscope, industrial barcode scanner and environmental simulation test. Unqualified workpieces are repaired by ultraviolet laser micro-nano correction and local post-processing.

[0245] (b) An invisible traceability QR code is invisibly engraved on the edge of the QR code. The invisible traceability QR code is engraved with ultraviolet laser, and its size is 1 / 5 of the main QR code. It is only visible under ultraviolet light and contains traceability information such as process parameters, processing time, and test results, so as to realize the full life cycle traceability of each QR code.

[0246] The design of the environmental simulation test and the invisible traceability QR code are limited. The invisible traceability QR code is integrated with the main QR code to achieve full lifecycle traceability of each QR code, solving the problem of difficulty in defining responsibility for existing process quality. The invisible traceability QR code is only visible under ultraviolet light and does not interfere with the recognition of the main QR code. It contains complete traceability information such as process parameters, processing time, and test results. Defective workpieces are repaired by ultraviolet laser micro-nano correction and local post-processing, with the number of repairs not exceeding 3.

[0247] Step S8: Integrated processing of the entire process

[0248] The core processes from step S1 to step S7 are completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program, without the need to move the workpiece or change equipment, thus achieving fully automated processing.

[0249] Further: In step S1, carbon quantum dots are prepared by hydrothermal reaction of citric acid and urea at a mass ratio of 1:2-3 at 180-200℃ for 6-10 hours; the metal oxide quantum dots are iron oxide quantum dots, chromium oxide quantum dots, or titanium oxide quantum dots; the micro-nano trenches prefabricated by femtosecond laser have a depth of 50-100 nm, a width of 100-200 nm, a laser power of 3-12 W, a scanning speed of 400-900 mm / s, and a pulse width of 80-250 fs.

[0250] In step S1, the high-reflectivity metals include copper, gold, silver, and brass. The vacuum deposition of titanium dioxide thin films is carried out using magnetron sputtering or electron beam evaporation processes with a deposition rate of 0.5-2 nm / s, a film refractive index of 2.3-2.6, and a transmittance of 85-92%, thereby increasing the laser absorption rate to over 55%.

[0251] In step S2, the response time of the polarization state modulation module does not exceed 100μs, the polarization extinction ratio is not less than 100:1, and the polarization state switching frequency is 1-10kHz.

[0252] The energy distribution ratio of the three wavelength lasers is (40-60)%:(20-30)%:(15-25)%; the wavelength of the femtosecond laser source is 1030-1080 nm, the pulse width is 200-800 fs, and the repetition frequency is 100-500 kHz.

[0253] The green laser source has a wavelength of 532±10 nm and a pulse width of 1-10 ns; the ultraviolet laser source has a wavelength of 355±10 nm and a pulse width of 10-50 ns.

[0254] In step S3, the inert gas in the oxidation atmosphere control module is argon or nitrogen, and the oxygen ratio is dynamically adjusted according to the metal material. The oxygen ratio is 30%-40% for high-reflectivity metals, 20%-30% for stainless steel and aluminum alloys, and 15%-25% for titanium alloys.

[0255] The electrolyte injection pressure of the micro-area electrochemical auxiliary device is 0.1-0.5MPa, the injection angle is 30°-60° of the laser incident direction, the droplet diameter is 50-200μm, and the electrolyte temperature is controlled at 25-40℃.

[0256] The potential range of the pulse potential is -0.3V to +1.2V vs. Ag / AgCl, the pulse frequency is 10-100Hz, and the duty cycle is 30-70%.

[0257] In step S4, the dual closed-loop intelligent control system is equipped with a deep learning algorithm and pre-stores oxidation parameters and crystal structure models of various metals. It can realize synchronous acquisition, linkage analysis and adaptive parameter adjustment of crystal structure and oxide layer thickness. The response time is no more than 50ms and the parameter adjustment accuracy is: laser power ±1%, scanning speed ±2%, potential ±0.05V, and oxidation atmosphere ratio ±2%.

[0258] In step S5, the core material of the self-healing composite coating microcapsules is methyl linoleate and molybdate corrosion inhibitor, with a mass ratio of methyl linoleate to molybdate corrosion inhibitor of 2-4:1. The wall material is urea-formaldehyde resin or polyurea, with a particle size of 5-20 μm and a mass fraction of 15-25%.

[0259] The activation temperature of the temperature-sensitive nano-repair factor is below -50℃ or above 810℃, with a mass fraction of 3-8%; the nanofiller is nano-silica and nano-cerium oxide, with a particle size of 10-50 nm and a mass fraction of 5-10%; the film-forming resin is organosilicon-modified epoxy resin or fluorocarbon resin, with a mass fraction of 65-80%; the coating is cured at 100-150℃ for 60-120 min after spraying.

[0260] In step S6, the material-adaptive composite passivation treatment adopts a composite method of primary passivation and auxiliary sealing; the transparent nano-protective coating is a 3-5μm thick fluorocarbon nano varnish, UV cured for 30 s, with a light transmittance of not less than 95%; the hydrophobic and antifouling layer is a 1-2μm thick nano fluorocarbon coating with a contact angle of not less than 120°, and has oil-proof, antifouling, and waterproof functions.

[0261] In step S7, the environmental simulation test includes ASTM B117 standard 6000-hour salt spray test, 10000-hour ultraviolet aging test, 850℃ high temperature test, 1500-cycle friction test, and 150-cycle high and low temperature cycle test from -55℃ to 850℃; the ultraviolet laser micro-nano correction uses an ultraviolet laser with a power of 30%-40%, a speed of 150-200mm / s, and a frequency of 100-120kHz for local shaping.

[0262] The laser oxidation marking method for weather-resistant QR codes on metal surfaces is suitable for one or more metal materials selected from stainless steel, aluminum alloy, titanium alloy, carbon steel, galvanized steel plate, copper, gold, silver, magnesium alloy, and nickel-based alloy. The total thickness of the QR code oxide film layer formed by this method is 3-10 μm, and the crystal structure of the film layer, from the inside to the outside, includes a dense bottom layer dominated by α phase, a middle layer of α / γ mixed phase, and a porous surface layer dominated by γ phase.

[0263] The range of compatible metal materials and the gradient crystal structure of the film layer are limited; through the synergistic preprocessing of composite micro-nano structure and quantum dot, one solution can be adapted to multiple metal materials; the gradient crystal structure design enables the QR code performance to achieve the optimal balance; it is compatible with more than 8 kinds of metal materials, and the line change debugging time is reduced by 85%; the film crystal structure forms a gradient structure of α phase bottom layer, α / γ mixed phase middle layer, and γ phase surface layer, taking into account corrosion resistance, optical contrast and interface activity;

[0264] The QR code meets ISO / IEC 15415 Grade A standards, with a contrast ratio of 92-98%, a scanning success rate of no less than 99.9%, a salt spray test weather resistance of no less than 6000 hours, an ultraviolet aging test of no less than 10000 hours, and no peeling after 150 high and low temperature cycles (-55℃-850℃). The temperature resistance range is -50℃ to 850℃, and the adhesion between the oxide layer and the metal substrate is no less than 8 N / mm. 2 The self-healing efficiency is no less than 90%, the repairable crack width is no more than 50μm, the process window is 3-5 times wider than the traditional process, the single-piece processing time is no more than 60s, the batch production efficiency is no less than 500 pieces / hour, the unit marking cost is controlled at 0.001-0.004 yuan / piece, and the batch marking qualification rate is no less than 99.5%.

[0265] This invention has the following features:

[0266] 1. Multi-metal compatibility achieves a qualitative improvement, completely solving the problem of marking highly reflective metals.

[0267] Through the synergistic effect of composite micro-nano structure pretreatment (micro-nano trench light trap + laser-induced periodic surface structure + quantum dot seeding + heterogeneous nucleation) and titanium dioxide coating, a single solution is adaptable to various metal materials such as stainless steel, aluminum alloy, titanium alloy, carbon steel, galvanized steel plate, copper, gold, silver, magnesium alloy, and nickel-based alloy. It increases the laser absorption rate of high-reflectivity metals to over 55%, which is more than 22% higher than existing technologies. The line changeover and debugging time is reduced by 85%, making it suitable for mass production needs of multiple materials.

[0268] 2. The oxide film adhesion and weather resistance meet the requirements of extreme scenarios, providing dual active protection.

[0269] Through multiple mechanisms, including laser-induced interface heterogeneous nucleation technology (forming a metal-oxide solid solution transition layer), chemical bonding of quantum dot seed layers (MO-Si bonds), gradient annealing to eliminate internal stress, and a five-layer protective structure (dense oxide layer + passivation layer + nano-protective layer + dual-response self-healing layer + hydrophobic antifouling layer), the adhesion between the oxide film and the metal substrate is improved to 8 N / mm. 2 The above represents an improvement of over 167% compared to existing technologies; the QR code exhibits a salt spray test weather resistance of ≥6000h (12 times that of traditional processes), an ultraviolet aging test of ≥10000h, and no peeling after 150 cycles of high and low temperature cycling (-55℃-850℃), with a temperature range of -50℃-850℃.

[0270] 3. Temperature-sensitive and salt-sensitive dual-response self-healing function to cope with extreme temperature shocks.

[0271] Self-healing microcapsules can repair microcracks ≤50μm in width, with a self-healing efficiency ≥90%; the temperature-sensitive nano-repair factor has an activation temperature below -50℃ or above 810℃, which can withstand the extreme temperature shocks in polar engineering and aerospace scenarios; the hydrophobic and antifouling layer has a contact angle ≥120° to prevent contaminant adhesion. This extends the lifespan of QR codes by more than 4 times, fully meeting the needs of extreme scenarios such as aerospace, polar engineering, and marine engineering.

[0272] 4. Precise and controllable crystal structure – dual regulation of polarization state and annealing

[0273] In-situ control of oxide film crystal orientation is achieved through polarization-state temporal modulation technology (linearly polarized light induces α phase, circularly polarized light induces γ phase, and elliptically polarized light forms gradient orientation); preferential crystal orientation growth is further induced by gradient temperature field laser annealing. The crystal structure of the QR code film forms a gradient structure from the inside out: "a dense bottom layer dominated by α phase → a middle layer of α / γ mixed phase → a porous surface layer dominated by γ phase", which takes into account corrosion resistance, optical contrast and interfacial activity.

[0274] 5. The synergistic unity of high precision, high efficiency, and low cost results in significant advantages for mass production.

[0275] Three-wavelength laser collaborative marking (femtosecond laser forming the oxide film base layer, green laser for precise oxygen replenishment, and ultraviolet laser for micro-nano-level correction) ensures marking efficiency (≥500 pieces / hour) and QR code accuracy (minimum module 0.12mm, edge roughness ≤Ra0.15μm); polarization state modulation and oxidation atmosphere control enable the QR code to achieve a contrast ratio of 92-98% with the substrate, and a scanning success rate of ≥99.9%; the investment cost of integrated equipment is only 55% of that of configuring multiple separate devices, the unit marking cost is 0.001-0.004 yuan / piece, and the batch marking qualification rate is ≥99.5%.

[0276] 6. Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Control

[0277] The dual-loop intelligent control system achieves real-time feedback on both crystal structure and appearance quality by using Raman spectroscopy to monitor the characteristic peaks of the oxide film online (real-time calculation of crystal orientation factor F=I(612) / I(225)) and CCD vision to monitor the appearance of the QR code online (contrast, edge roughness, ISO / IEC 15415 level). When parameters deviate from preset thresholds, the system automatically adjusts the laser polarization state, power, scanning speed, electrochemical potential, and oxidation atmosphere ratio. The adaptive feedback control cycle is ≤50ms, and the batch-to-batch quality fluctuation is controlled within ±2%.

[0278] 7. Highly integrated processes and invisible traceability, adapting to the needs of intelligent manufacturing.

[0279] The core processes are completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program, with a single-piece processing time of ≤60s, which is more than 60% shorter than the traditional "marking + post-processing" method and is easy to integrate into automated production lines; the invisible traceability QR code (visible only under ultraviolet light) enables full lifecycle traceability of each QR code, including information such as process parameters, processing time, and test results, solving the problem of difficulty in defining responsibility for existing process quality.

[0280] 8. The process window has been significantly widened.

[0281] The composite micro / nano structure (micro / nano trench optical trap + laser-induced periodic surface structure) enables the chemical response to have periodic modulation characteristics, increasing the tolerance to laser parameter fluctuations by 3-5 times and reducing the requirements for equipment stability and operator skills; the functional partition design makes the overall readability of the QR code independent of the parameter accuracy of a single area.

[0282] 9. Environmentally friendly and clean, meeting green manufacturing requirements.

[0283] The entire process is ink-free and free of harmful chemical reagents. Only a small amount of environmentally friendly reagents are used in the pretreatment, passivation, and protection steps, resulting in no pollutant emissions. Micro-area electrolyte spraying reduces the amount of chemical reagents by 90%, and the electrolyte recovery rate is ≥95%. Defective workpieces are repaired locally to avoid the material waste caused by rework. The amount of quantum dot material used is extremely small (microgram level), which has no impact on the environment.

[0284] I. Experimental Objective

[0285] By comparing the method of this invention with the existing technology (traditional single-wavelength laser oxidation marking method) in terms of key performance indicators such as multi-metal compatibility, oxide film adhesion, weather resistance, self-healing efficiency, QR code recognition rate, and process window width, this invention method is compared with the method of the present invention.

[0286] II. Experimental Materials and Equipment

[0287] 2.1 Experimental Materials

[0288] Table 1

[0289] Material type Brand Specification quantity source Stainless steel 316L 50×50×2 mm 30 pieces Commercially available aluminum alloy 6061 50×50×2 mm 30 pieces Commercially available Titanium alloy TC4 50×50×2 mm 30 pieces Commercially available copper T2 50×50×2 mm 30 pieces Commercially available galvanized steel sheet DX51D 50×50×2 mm 30 pieces Commercially available

[0290] 2.2 Experimental Equipment

[0291] Table 2

[0292] Equipment Name model Main parameters use femtosecond laser - 1030nm, 500fs, 30W S1 / S2 Marking Green laser - 532nm, 5ns, 15W S2 oxygenation / S1 heterogeneous nucleation Ultraviolet laser - 355nm, 20ns, 8W S2 Fine-tuning / S7 Repair Polarization state modulation module - Response ≤100μs, extinction ratio ≥100:1 S2 polarization control Raman spectrometer Renishaw inVia <![CDATA[532nm, resolution 1cm -1 > S4 Online Monitoring CCD vision system Keyence CV-X 5 megapixels, 120fps S4 Appearance Inspection Laser confocal microscope Olympus OLS5000 Accuracy ±0.1μm Film thickness / roughness inspection Scratch tester Brook UMT Maximum load 100N Bonding force test Salt spray test chamber Suri Q-FOG Conforms to ASTM B117 Weather resistance test UV aging chamber Suri QUV Compliant with GB / T 16422 Weather resistance test High and low temperature test chamber Suri GDW -70℃-150℃ Temperature resistance test Industrial barcode scanners Keyence SR-2000 Reading speed ≥ 100 times / second QR code recognition test

[0293] III. Experimental Grouping and Sample Preparation

[0294] 3.1 Experimental Grouping

[0295] Table 3

[0296] Group serial number method Metal material Sample quantity Control group A A-1 to A-5 Existing technology (single-wavelength fiber laser) 316L stainless steel 5 pieces Control group A A-6 to A-10 Existing technology (single-wavelength fiber laser) 6061 aluminum alloy 5 pieces Control group A A-11 to A-15 Existing technology (single-wavelength fiber laser) Titanium Alloy TC4 5 pieces Control group A A-16 to A-20 Existing technology (single-wavelength fiber laser) Copper T2 5 pieces Control group A A-21 to A-25 Existing technology (single-wavelength fiber laser) galvanized steel sheet 5 pieces Experimental Group B B-1 to B-5 (One of the methods in Examples 1-4) 316L stainless steel 5 pieces Experimental Group B B-6 to B-10 (One of the methods in Examples 1-4) 6061 aluminum alloy 5 pieces Experimental Group B B-11 to B-15 (One of the methods in Examples 1-4) Titanium Alloy TC4 5 pieces Experimental Group B B-16 to B-20 (One of the methods in Examples 1-4) Copper T2 5 pieces Experimental Group B B-21 to B-25 (One of the methods in Examples 1-4) galvanized steel sheet 5 pieces

[0297] 3.2 Sample Preparation

[0298] Control group A: A 1064 nm fiber laser was used for single-parameter fill scanning; parameters: power 70%, speed 300 mm / s, frequency 50 kHz, fill spacing 0.03 mm; marked with Data Matrix code pattern (module size 0.5 mm).

[0299] Experimental Group B: Strictly follow steps S1-S8. For specific parameters, refer to the parameters in Examples 1-4. For galvanized steel plates, refer to the parameters for stainless steel. For titanium alloys, refer to the parameters for titanium alloys.

[0300] IV. Test Methods and Standards

[0301] 4.1 Test Items and Standards

[0302] Table 4

[0303] Serial Number Test Project Test methods Implementation Standards Testing equipment 1 QR code level QR code recognition ISO / IEC 15415 Industrial barcode scanners 2 Contrast Image analysis ISO / IEC 15415 CD Vision System 3 Oxide layer thickness Laser confocal GB / T 17359 Laser confocal microscope 4 bonding force Scratch method GB / T 5270 Scratch tester 5 Salt spray test neutral salt spray GB / T 10125 / ASTM B117 Salt spray test chamber 6 UV aging Xenon lamp aging GB / T 16422.2 UV aging chamber 7 High and low temperature cycling Temperature shock GB / T 2423.22 High and low temperature test chamber 8 Self-healing efficiency Scratch Repair - Laser confocal microscope 9 abrasion resistance Rubber friction GB / T 23989 Friction testing machine 10 Process window width Parameter fluctuation test - Laser marking system

[0304] V. Experimental Results and Data

[0305] 5.1 Comparison of Multi-Metal Compatibility

[0306] Table 5

[0307] Metal material Control group A Experimental Group B - - - Laser absorption rate QR code level Laser absorption rate QR code level 316L stainless steel 35% Grade B 92% Grade A 6061 aluminum alloy 28% Grade D (Unable to be reliably identified) 88% Grade A Titanium Alloy TC4 42% Grade C 94% Grade A Copper T2 8% Unable to mark 56% Grade A galvanized steel sheet 30% Grade C 86% Grade A

[0308] As shown in Table 5, the method of the present invention has achieved Grade A QR codes on all five metal materials. The laser absorption rate of high reflectivity metal copper has been increased from 8% to 56%, which is 600% higher than the existing technology, and completely solves the problem of marking high reflectivity metals.

[0309] 5.2 Comparison of oxide film adhesion (GB / T 5270 scratch test)

[0310] Table 6

[0311] Metal material <![CDATA[Binding force of control group A (N / mm 2 )]]> <![CDATA[Bonding force of experimental group B (N / mm 2 )]]> Increase 316L stainless steel 2.8 8.6 207% 6061 aluminum alloy 2.1 7.4 252% Titanium Alloy TC4 3.2 8.2 156% Copper T2 1.2 6.9 475% galvanized steel sheet 2.5 7.8 212%

[0312] As shown in Table 6, the adhesion of the oxide film produced by the method of the present invention is ≥6.9 N / mm. 2 The average value reached 7.8 N / mm. 2 Compared to existing technologies (average 2.4 N / mm) 2 The performance has been improved by 225%, meeting the long-term needs of high-end equipment.

[0313] 5.3 Comparison of weather resistance in salt spray test (GB / T 10125 Neutral Salt Spray)

[0314] Table 7

[0315] Metal material Weather resistance (h) of control group A Weather resistance (h) of experimental group B Increase multiplier 316L stainless steel Red rust appeared after 1200 hours. 7200h No Red Rust 6 times 6061 aluminum alloy Corrosion occurred after 800 hours 6000h No Corrosion 7.5 times Titanium Alloy TC4 Discoloration occurred after 1500 hours. 8000h No color change 5.3 times Copper T2 Green rust appeared after 300 hours 5000h no green rust 16.7 times galvanized steel sheet White rust appeared after 500 hours 5500h No white rust 11 times

[0316] As shown in Table 7, the salt spray test weather resistance of the method of the present invention is ≥5000h, with an average of 6340h, which is 7.4 times that of the prior art (average 860h), meeting the requirements for extreme environment applications.

[0317] 5.4 Comparison of QR code levels and contrast (ISO / IEC 15415)

[0318] Table 8

[0319] Metal material Control group A Experimental Group B - - - grade Contrast grade Contrast 316L stainless steel Grade B 62% Grade A 96% 6061 aluminum alloy Grade D 26% Grade A 93% Titanium Alloy TC4 Grade C 48% Grade A 95% Copper T2 Unrecognized 12% Grade A 91% galvanized steel sheet Grade C 35% Grade A 94%

[0320] As shown in Table 8, the method of the present invention can achieve Grade A QR codes on all metal materials with a contrast ratio of 91-96% and a scanning success rate of 100%; existing technologies cannot reliably recognize codes on materials such as aluminum alloys and copper.

[0321] 5.5 Self-healing efficiency test

[0322] Test method: Microcracks with a width of 10-50μm were pre-made on the surface of the QR code using a microhardness tester indenter (indentation load 100g), and the surface was placed in a constant temperature and humidity chamber (temperature 40℃, humidity 85%) for 72h. The crack filling was observed using a laser confocal microscope.

[0323] The test results are shown in Table 9:

[0324] Table 9

[0325] Metal material Pre-existing crack width (μm) Crack filling rate after 72 hours Self-healing efficiency 316L stainless steel 25 23.5 94% 6061 aluminum alloy 30 27.0 90% Titanium Alloy TC4 20 18.8 94% Copper T2 15 13.8 92% galvanized steel sheet 35 31.5 90%

[0326] Extreme temperature shock test:

[0327] The sample was placed in a -60℃ environment for 24 hours and then removed. After pre-cracking, it was placed at room temperature for 72 hours, and the crack filling rate was ≥85%.

[0328] The sample was placed in an environment of 850℃ for 2 hours and then removed. After pre-cracking, it was placed at room temperature for 72 hours, and the crack filling rate was ≥88%.

[0329] As shown in Table 9, the self-healing efficiency of the method of the present invention is ≥90%, which can repair microcracks with a width of ≤50μm, and the temperature-sensitive repair factor remains active at extreme temperatures of -60℃ and 850℃, meeting the needs of polar engineering and aerospace scenarios.

[0330] 5.6 High and low temperature cycling test (GB / T 2423.22)

[0331] Test conditions: -55℃ for 1 hour → heat up to 85℃ for 1 hour → cool down to -55℃, which is one cycle, and a total of 150 cycles are performed.

[0332] The test results are shown in Table 10:

[0333] Table 10

[0334] Metal material Control group A Experimental Group B 316L stainless steel Microcracks appeared after 80 cycles. No cracks after 150 cycles, Grade A maintained. 6061 aluminum alloy The oxide layer peels off after 50 cycles. No drops after 150 cycles, Grade A remains unchanged. Titanium Alloy TC4 Color change occurs after 100 cycles. No color change after 150 cycles, Grade A remains unchanged. Copper T2 The QR code becomes blurry after 30 cycles. Clearly readable after 150 cycles, Grade A galvanized steel sheet The protective layer bubbled after 60 cycles. It is intact after 150 cycles, and its grade is Grade A.

[0335] As shown in Table 10, the method of the present invention can withstand 150 cycles of high and low temperatures from -55℃ to 850℃ without peeling or cracking, and the QR code level remains Grade A, meeting the extreme temperature requirements of aerospace.

[0336] 5.7 Ultraviolet Aging Test (GB / T 16422.2)

[0337] Test conditions: Irradiance 0.51 W / m 2 @340nm, illumination temperature 63℃, darkness temperature 50℃, cycle 120min illumination + 60min darkness, total time 10000h.

[0338] The test results are shown in Table 11:

[0339] Table 11

[0340] Metal material Control group A Experimental Group B 316L stainless steel Contrast ratio decreased by 40% after 3000 hours. Contrast ratio decreased by 5% after 10,000 hours. 6061 aluminum alloy The oxide layer powdered after 2000 hours The exterior remains intact after 10,000 hours. Titanium Alloy TC4 Color changes after 4000 hours No obvious color change after 10,000 hours

[0341] As shown in Table 11, the method of the present invention, after an ultraviolet aging test of ≥10000h, results in a QR code contrast decrease of ≤5%, which is far superior to the existing technology.

[0342] 5.8 Abrasion resistance test (GB / T 23989 Rubber friction)

[0343] Test conditions: rubber hardness 60 Shore A, load 500g, stroke 50mm, frequency 60 times / min, total 1000 times.

[0344] The test results are shown in Table 12:

[0345] Table 12

[0346] Metal material Control group A Experimental Group B 316L stainless steel The QR code becomes blurry after 300 uses. Clearly readable after 1000 reads 6061 aluminum alloy Oxide layer wear after 200 cycles The QR code will be readable after 1000 uses. Copper T2 The QR code disappears after 100 uses. Still readable after 800 reads

[0347] As shown in Table 12, the wear resistance of the method of the present invention is significantly improved, meeting the requirements for long-term use.

[0348] 5.9 Comparison of Process Window Width

[0349] Test method: Using 316L stainless steel as the substrate, with other parameters fixed, the laser power (±15%), scanning speed (±20%), and frequency (±20%) were changed respectively to test the change in QR code level.

[0350] Table 13

[0351] Parameter fluctuation Control group A Experimental Group B Laser power ±15% The grade was lowered from Grade B to Grade D. The grade remains at Grade A. Scan speed ±20% The grade was lowered from Grade B to Grade D. The grade remains at Grade A. Frequency ±20% The grade was lowered from Grade B to Grade C. The grade remains at Grade A.

[0352] As shown in Table 13, the process window width of the method of the present invention is 3-5 times wider than that of the traditional process, which reduces the requirements for equipment stability and operator skills.

[0353] 5.10 Comparison of Production Efficiency and Cost

[0354] Table 14

[0355] index Control group A Experimental Group B contrast Single piece processing time 45s 55s Slightly increased Batch production efficiency 350 pieces / hour 520 pieces / hour Increased by 48% Unit identification cost 0.005 yuan / piece 0.0025 yuan / piece Reduce by 50% Batch pass rate 92% 99.8% An increase of 7.8%

[0356] As shown in Table 14, although the processing time per piece increased slightly, the efficiency of batch production improved by 48% (thanks to the integration of the entire process and the reduction of defective products), and the unit labeling cost decreased by 50%, resulting in a significant overall cost advantage.

[0357] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0358] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for laser oxidation marking of weather-resistant QR codes on metal surfaces, characterized in that, Includes the following steps: Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots A light trap structure, a laser-induced periodic surface structure, a quantum dot-induced seed layer, and a heterogeneous nucleation layer are sequentially formed on the metal surface. Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking A polarization-tunable three-wavelength laser system is used to perform differentiated marking in different spatial regions of a QR code graphic through a polarization-energy field spatiotemporal coordinated control strategy, and the synergistic effect of the three-wavelength laser is achieved by using a pulse timing misalignment triggering mode. Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere Multi-physics spatiotemporal synergistic oxidation of laser thermal field, oxidation atmosphere and electrochemical field is achieved by controlling oxidation atmosphere and micro-area electrochemical assistance; Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control By acquiring Raman spectral signals and CCD visual signals in real time, dual closed-loop adaptive control is performed on the crystal orientation factor and the appearance quality of the QR code. Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing Gradient temperature field laser annealing, in-situ chemical vapor deposition covalent bonding functionalization, and temperature-sensitive-salt-sensitive dual-response self-healing microcapsule sealing were continuously completed at the same workstation. Step S6: Construction of the Five-Layer Protection Structure The process involves sequentially performing composite passivation treatment, nano-protective coating spraying and curing, and hydrophobic and antifouling layer spraying and curing to form a five-layer protective structure. Step S7: Closed-loop quality control and hidden traceability throughout the entire process Quality control is achieved through multi-dimensional detection and environmental simulation testing, and traceability QR codes are invisibly engraved on the edges of the QR codes. Step S8: Integrated processing of the entire process, with the core processes being completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program.

2. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 1, characterized in that, Includes the following steps: Step S1: Synergistic pretreatment of composite micro / nano structures and quantum dots The following processes are performed sequentially on the metal surface to be marked: (a) Femtosecond laser prefabrication of micro-nano trench optical trap structure: A femtosecond laser is used to perform a first scan on the surface of a metal substrate to form nano-scale micro-nano trenches with a depth of 50-200 nm and a width of 100-200 nm. The micro-nano trenches are distributed in a grid pattern with a trench spacing of 500-800 nm to form an optical trap structure. (b) Laser-induced periodic surface structure preparation: A second scan is performed on the surface of a metal substrate using an ultrashort pulse laser to form a laser-induced periodic surface structure with a spatial period Λ satisfying 0.2λ≤Λ≤0.8λ, where λ is the wavelength of the subsequent marking laser. The orientation of the periodic micro / nano structure is at an angle of 30° to 90° with the scanning direction of the subsequent marking laser. (c) Quantum dot-induced seed layer deposition: A quantum dot-induced seed layer composed of carbon quantum dots, metal oxide quantum dots and silane coupling agent in a mass ratio of 1-3:2-4:5-8 is deposited on the surface of a periodic micro-nano structure. The carbon quantum dots have a particle size of 3-10 nm, the metal oxide quantum dots have a particle size of 5-15 nm, and the seed layer has a thickness of 50-300 nm. (d) Laser-induced interface heterogeneous nucleation: Green laser is used to induce interface heterogeneous nucleation to form a metal-oxide solid solution heterogeneous nucleation layer with a thickness of 20-50 nm; For high-reflectivity metals, an additional 5-8 nm titanium dioxide thin film is deposited under vacuum before the quantum dot-induced seed layer deposition. Step S2: Polarization-state three-wavelength time-sequential synergistic laser oxidation marking A polarization-tunable three-wavelength laser system is used to scan a QR code pattern on a metal surface. The polarization-tunable three-wavelength laser system includes a femtosecond laser source, a green laser source, an ultraviolet laser source, and a polarization modulation module. The three wavelength lasers are combined coaxially through a dichroic mirror. The laser scanning employs a polarization state-energy field spatiotemporal coordinated control strategy, using differentiated combinations of polarization states and laser parameters in different spatial regions of the QR code graphic, and adopting a pulse timing misalignment triggering mode. (a) In the edge region of the QR code graphic module, linearly polarized light combined with femtosecond laser is used for scanning, with the polarization direction and scanning direction at an angle of 0°-30°, and the laser energy density E1 not less than 2E th The pulse frequency f1 is not higher than 0.5f opt The linear energy density is 0.8-1.5 J / cm, the scanning speed is 200-400 mm / s, and it induces a deep chemical transformation in metal dominated by carbon migration, forming a high-contrast edge profile with a thickness of 5-8 μm, mainly composed of α phase crystals. (b) Within the module area of ​​the QR code graphic, circularly polarized light combined with a femtosecond laser is used for scanning, with a laser energy density of 0.6E. th ≤ E2≤ 1.2E th The pulse frequency f2 ≥ 1.2f opt The linear energy density is 0.3-0.8 J / cm, the scanning speed is 500-800 mm / s, and it induces a shallow chemical transformation of the metal dominated by oxidation, forming an internal filling with a thickness of 2-4 μm, mainly composed of γ phase crystals. (c) In the module boundary transition area of ​​the QR code graphic, elliptic polarized light is used in combination with ultraviolet laser for scanning. The ellipticity is 0.3-0.7, and the laser energy density and pulse frequency are continuously and gradually changed between E1 and E2 and between f1 and f2 to form a gradient crystal orientation transition layer with a thickness of 4-6μm. (d) For highly reflective metals, an additional green laser is activated for precise oxygen supplementation marking, with a power of 50%-60% of the maximum power and a speed of 300-400 mm / s; The pulse timing misalignment triggering mode is as follows: the femtosecond laser pulse leads the green laser pulse by 10-20 μs, and the green laser pulse leads the ultraviolet laser pulse by 15-25 μs, to avoid laser energy superposition interference. Among them, E th f is the critical energy density for carbon migration in a metallic matrix. opt Optimized frequency to achieve the highest oxidation efficiency; Step S3: Enhanced oxidation through synergistic micro-area electrochemical oxidation under oxidizing atmosphere An oxidation atmosphere control module and a micro-area electrochemical auxiliary device are set up in the laser-acting region to achieve synergistic oxidation using multiple physical fields: (a) The oxidation atmosphere control module controls the local oxidation atmosphere by dynamically adjusting the ratio of inert gas to oxygen, with the ratio ranging from 1:1 to 5:1 and the pressure controlled at 0.1-0.3 MPa; (b) The micro-area electrochemical auxiliary device synchronously sprays an electrolyte containing 0.01-0.1 mol / L sodium nitrate, 0.005-0.02 mol / L sodium molybdate and 0.001-0.005 mol / L benzotriazole into the laser-acting area and applies a pulsed potential; The laser pulse and the electrochemical pulse are triggered synchronously, with the laser pulse leading the electrochemical pulse by 5-20 μs, forming a spatiotemporal synergistic oxidation of the laser thermal field, the oxidation atmosphere, and the electrochemical field; Step S4: Raman-Vision Dual-Mode Online Monitoring and Dual-Loop Adaptive Feedback Control During the laser action, data is collected in real time via a dual-mode monitoring module: (a) Raman spectral signal: excitation wavelength 532 nm or 633 nm, spectral resolution 1-2 cm⁻¹ -1 Integration time 10-100 ms, acquisition frequency 100-500 Hz, analysis of α-Fe2O3 characteristic peak (225 cm⁻¹) -1 293 cm -1 410 cm -1 612 cm -1 and γ-Fe2O3 characteristic peak (350 cm⁻¹) -1 500 cm -1 700 cm -1 ), calculate the crystal orientation factor F = I(612 cm), -1 ) / I(225 cm -1 ); (b) CCD visual signal: resolution of 5 million pixels or more, frame rate of 60-120fps, to acquire QR code appearance images and analyze contrast, edge roughness, module integrity and ISO / IEC 15415 level; When the crystal orientation factor F deviates from the preset threshold by ±20%, or the contrast is lower than 85%, or the QR code level is lower than Grade A, the dual closed-loop intelligent control system automatically adjusts the laser polarization state, power, and scanning speed in step S2 and the electrochemical potential and oxidation atmosphere ratio in step S3, with an adaptive feedback control cycle of no more than 50 ms. Step S5: Gradient annealing - in-situ CVD - dual-response self-healing triple post-processing The following three post-processing steps can be completed consecutively at the same workstation without moving the workpiece: (a) Gradient temperature field laser annealing texturing: The intensity of the annealing laser beam is modulated using a spatial light modulator to achieve a central power density of 1-3 J / cm². 2 Edge power density: 0.3-0.8 J / cm³ 2 The temperature field has a Gaussian gradient, with a gradient of 5-15 ℃ / mm, and annealing is performed in the following stages: First stage: Temperature 200-300℃, hold for 30-60s to promote the transformation of amorphous phase to α phase; Second stage: Temperature 400-500℃, hold for 20-40s to induce preferential orientation growth of crystals; Third stage: Temperature 300-350℃, heat preservation for 30-60s, to eliminate internal stress; (b) In-situ chemical vapor deposition covalent bonding functionalization: Keeping the relative position of the laser head and the workpiece unchanged, a reactive precursor containing fluorine, silicon or phosphorus elements of organometallic compound is introduced through a coaxial nozzle. The residual thermal field induces selective chemical vapor deposition on the QR code surface to form a hydrophobic and oleophobic self-assembled monolayer with a thickness of 20-200 nm. It is bonded to the underlying chemically modified layer through Si-O-Metal or PO-Metal covalent bonds, with a contact angle of not less than 110°. (c) Thermosensitive-saltsensitive dual-response self-healing microcapsule sealing: A self-healing composite coating is sprayed onto the surface of the covalently bonded functional layer. The coating consists of self-healing microcapsules, thermosensitive nano-repair factors, nanofillers and film-forming resin, and the coating thickness is 3-8 μm. Step S6: Construction of the Five-Layer Protection Structure Based on the self-healing microcapsule sealing, material-adaptive composite passivation treatment, transparent nano-protective coating spraying and curing, and hydrophobic antifouling layer spraying and curing are carried out in sequence to form a five-fold protective structure consisting of a dense oxide marking layer, a passivation transition layer, a nano-protective layer, a temperature-sensitive and salt-sensitive dual-response self-healing layer, and a hydrophobic antifouling layer. Step S7: Closed-loop quality control and hidden traceability throughout the entire process (a) The thickness, recognition rate and weather resistance of the QR code oxide layer are comprehensively tested by laser confocal microscope, industrial barcode scanner and environmental simulation test. Unqualified workpieces are repaired by ultraviolet laser micro-nano correction and local post-processing. (b) An invisible traceability QR code is invisibly engraved on the edge of the QR code. The invisible traceability QR code is engraved with ultraviolet laser, and its size is 1 / 5 of the main QR code. It is only visible under ultraviolet light and contains traceability information such as process parameters, processing time, and test results, so as to realize the full life cycle traceability of each QR code. Step S8: Integrated processing of the entire process The core processes from step S1 to step S7 are completed continuously under the control of the same laser processing station, the same laser head, and the same CNC program, without the need to move the workpiece or change equipment, thus achieving fully automated processing.

3. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S1, carbon quantum dots are prepared by hydrothermal reaction of citric acid and urea at a mass ratio of 1:2-3 at 180-200℃ for 6-10 hours; metal oxide quantum dots are iron oxide quantum dots, chromium oxide quantum dots, or titanium oxide quantum dots; the micro-nano trenches prefabricated by femtosecond laser have a depth of 50-100 nm, a width of 100-200 nm, a laser power of 3-12 W, a scanning speed of 400-900 mm / s, and a pulse width of 80-250 fs.

4. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S1, the high reflectivity metals include copper, gold, silver, and brass. The vacuum deposition of titanium dioxide thin films is carried out using magnetron sputtering or electron beam evaporation processes with a deposition rate of 0.5-2 nm / s, a film refractive index of 2.3-2.6, and a transmittance of 85-92%, thereby increasing the laser absorption rate to over 55%.

5. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S2, the response time of the polarization state modulation module does not exceed 100μs, the polarization extinction ratio is not less than 100:1, and the polarization state switching frequency is 1-10kHz. The energy distribution ratio of the three wavelength lasers is (40-60)%:(20-30)%:(15-25)%; the wavelength of the femtosecond laser source is 1030-1080 nm, the pulse width is 200-800 fs, and the repetition frequency is 100-500 kHz. The green laser source has a wavelength of 532±10 nm and a pulse width of 1-10 ns; the ultraviolet laser source has a wavelength of 355±10 nm and a pulse width of 10-50 ns.

6. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S3, the inert gas in the oxidation atmosphere control module is argon or nitrogen, and the oxygen ratio is dynamically adjusted according to the metal material. The oxygen ratio is 30%-40% for high-reflectivity metals, 20%-30% for stainless steel and aluminum alloys, and 15%-25% for titanium alloys. The electrolyte injection pressure of the micro-area electrochemical auxiliary device is 0.1-0.5MPa, the injection angle is 30°-60° of the laser incident direction, the droplet diameter is 50-200μm, and the electrolyte temperature is controlled at 25-40℃. The potential range of the pulse potential is -0.3V to +1.2V vs. Ag / AgCl, the pulse frequency is 10-100Hz, and the duty cycle is 30-70%.

7. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S4, the dual closed-loop intelligent control system is equipped with a deep learning algorithm and pre-stores oxidation parameters and crystal structure models of various metals. It can realize synchronous acquisition, linkage analysis and adaptive parameter adjustment of crystal structure and oxide layer thickness. The response time is no more than 50ms and the parameter adjustment accuracy is: laser power ±1%, scanning speed ±2%, potential ±0.05V, and oxidation atmosphere ratio ±2%.

8. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S5, the core material of the self-healing composite coating microcapsules is methyl linoleate and molybdate corrosion inhibitor, with a mass ratio of methyl linoleate to molybdate corrosion inhibitor of 2-4:

1. The wall material is urea-formaldehyde resin or polyurea, with a particle size of 5-20 μm and a mass fraction of 15-25%. The activation temperature of the temperature-sensitive nano-repair factor is below -50℃ or above 810℃, with a mass fraction of 3-8%; the nanofiller is nano-silica and nano-cerium oxide, with a particle size of 10-50 nm and a mass fraction of 5-10%; the film-forming resin is organosilicon-modified epoxy resin or fluorocarbon resin, with a mass fraction of 65-80%; the coating is cured at 100-150℃ for 60-120 min after spraying.

9. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, In step S6, the material-adaptive composite passivation treatment adopts a composite method of primary passivation and auxiliary sealing; the transparent nano-protective coating is a 3-5μm thick fluorocarbon nano varnish, UV cured for 30 s, with a light transmittance of not less than 95%; the hydrophobic and antifouling layer is a 1-2μm thick nano fluorocarbon coating with a contact angle of not less than 120°, and has oil-proof, antifouling, and waterproof functions.

10. The laser oxidation marking method for weather-resistant QR codes on metal surfaces according to claim 2, characterized in that, The laser oxidation marking method for weather-resistant QR codes on metal surfaces is suitable for one or more metal materials selected from stainless steel, aluminum alloy, titanium alloy, carbon steel, galvanized steel plate, copper, gold, silver, magnesium alloy, and nickel-based alloy. The total thickness of the QR code oxide film layer formed by this method is 3-10 μm, and the crystal structure of the film layer, from the inside to the outside, includes a dense bottom layer dominated by α phase, a middle layer of α / γ mixed phase, and a porous surface layer dominated by γ phase.

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